(Slip Opinion)              OCTOBER TERM, 2010                                       1

                                       Syllabus

         NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
       being done in connection with this case, at the time the opinion is issued.
       The syllabus constitutes no part of the opinion of the Court but has been
       prepared by the Reporter of Decisions for the convenience of the reader.
       See United States v. Detroit Timber & Lumber Co., 

, 337.


SUPREME COURT OF THE UNITED STATES

                                       Syllabus

                  PLIVA, INC., ET AL. v. MENSING

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
                 THE EIGHTH CIRCUIT

     No. 09–993.      Argued March 30, 2011—Decided June 23, 2011*
Five years after the Food and Drug Administration (FDA) first ap
  proved metoclopramide, a drug commonly used to treat digestive
  tract problems, under the brand name Reglan, generic manufacturers
  such as petitioners also began producing the drug. Because of accu
  mulating evidence that long-term metoclopramide use can cause
  tardive dyskinesia, a severe neurological disorder, warning labels for
  the drug have been strengthened and clarified several times, most re
  cently in 2009.
    Respondents were prescribed Reglan in 2001 and 2002, but both
  received the generic drug from their pharmacists. After taking the
  drug as prescribed for several years, both developed tardive dyskine
  sia. In separate state-court tort actions, they sued petitioners, the
  generic drug manufacturers that produced the metoclopramide they
  took (Manufacturers). Each respondent alleged, inter alia, that long
  term metoclopramide use caused her disorder and that the Manufac
  turers were liable under state tort law for failing to provide adequate
  warning labels. In both suits, the Manufacturers urged that federal
  statutes and FDA regulations pre-empted the state tort claims by re
  quiring the same safety and efficacy labeling for generic metoclopra
  mide as was mandated at the time for Reglan. The Fifth and Eighth
  Circuits rejected these arguments, holding that respondents’ claims
  were not pre-empted.
Held: The judgment is reversed, and the cases are remanded.
——————
  * Together with No. 09–1039, Actavis Elizabeth, LLC v. Mensing, also
on certiorari to the same court, and No. 09–1501, Actavis, Inc. v. De
mahy, on certiorari to the United States Court of Appeals for the Fifth
Circuit.
2                     PLIVA, INC. v. MENSING

                                Syllabus

and 

, reversed and remanded.
     JUSTICE THOMAS delivered the opinion of the Court with respect to
  all but Part III–B–2, concluding that federal drug regulations appli
  cable to generic drug manufacturers directly conflict with, and thus
  pre-empt, these state claims. Pp. 4–14, 17–20.
     (a) Because pre-emption analysis requires a comparison between
  federal and state law, the Court begins by identifying the state tort
  duties and federal labeling requirements applicable to the Manufac
  turers. Pp. 4–10.
       (1) State tort law requires a manufacturer that is, or should be,
  aware of its drug’s danger to label it in a way that renders it rea
  sonably safe. Respondents pleaded that the Manufacturers knew, or
  should have known, both that the long-term use of their products car
  ried a high risk of tardive dyskinesia and that their labels did not
  adequately warn of that risk. Taking these allegations as true, the
  state-law duty required the Manufacturers to use a different,
  stronger label than the one they actually used. Pp. 4–5.
       (2) On the other hand, federal drug regulations, as interpreted by
  the FDA, prevented the Manufacturers from independently changing
  their generic drugs’ safety labels. A manufacturer seeking federal
  approval to market a new drug must prove that it is safe and effec
  tive and that the proposed label is accurate and adequate. Although
  the same rules originally applied to all drugs, the 1984 law commonly
  called the Hatch-Waxman Amendments allows a generic drug manu
  facturer to gain FDA approval simply by showing that its drug is
  equivalent to an already-approved brand-name drug, and that the
  safety and efficacy labeling proposed for its drug is the same as that
  approved for the brand-name drug. Respondents contend that fed
  eral law nevertheless provides avenues through which the Manufac
  turers could have altered their metoclopramide labels in time to pre
  vent the injuries here. These include: (1) the FDA’s “changes-being
  effected” (CBE) process, which permits drug manufacturers, without
  preapproval, to add or strengthen a warning label; and (2) sending
  “Dear Doctor” letters providing additional warnings to prescribing
  physicians and other healthcare professionals. However, the FDA
  denies that the Manufacturers could have used either of these proc
  esses to unilaterally strengthen their warning labels. The Court de
  fers to the FDA’s views because they are not plainly erroneous or in
  consistent with the regulations, and there is no other reason to doubt
  that they reflect the FDA’s fair and considered judgment. Auer v.
  Robbins, 

, 461, 462. Assuming, without deciding, that
  the FDA is correct that federal law nevertheless required the Manu
  facturers to ask for the agency’s assistance in convincing the brand
  name manufacturer to adopt a stronger label, the Court turns to the
                   Cite as: 564 U. S. ____ (2011)                    3

                              Syllabus

pre-emption question. Pp. 5–10.
   (b) Where state and federal law directly conflict, state law must
give way. See, e.g., Wyeth v. Levine, 

, 583. Such a con
flict exists where it is “impossible for a private party to comply with
both state and federal requirements.” Freightliner Corp. v. Myrick,

, 287. Pp. 11–14, 17–20.
      (1) The Court finds impossibility here. If the Manufacturers had
independently changed their labels to satisfy their state-law duty to
attach a safer label to their generic metoclopramide, they would have
violated the federal requirement that generic drug labels be the same
as the corresponding brand-name drug labels. Thus, it was impossi
ble for them to comply with both state and federal law. And even if
they had fulfilled their federal duty to ask for FDA help in strength
ening the corresponding brand-name label, assuming such a duty ex
ists, they would not have satisfied their state tort-law duty. State
law demanded a safer label; it did not require communication with
the FDA about the possibility of a safer label. Pp. 11–12.
      (2) The Court rejects the argument that the Manufacturers’ pre
emption defense fails because they failed to ask the FDA for help in
changing the corresponding brand-name label. The proper question
for “impossibility” analysis is whether the private party could inde
pendently do under federal law what state law requires of it. See

. Accepting respondents’ argument would render
conflict pre-emption largely meaningless by making most conflicts be
tween state and federal law illusory. In these cases, it is possible
that, had the Manufacturers asked the FDA for help, they might
have eventually been able to strengthen their warning label. But it
is also possible that they could have convinced the FDA to reinterpret
its regulations in a manner that would have opened the CBE process
to them, persuaded the FDA to rewrite its generic drug regulations
entirely, or talked Congress into amending the Hatch-Waxman
Amendments. If these conjectures sufficed to prevent federal and
state law from conflicting, it is unclear when, outside of express pre
emption, the Supremacy Clause would have any force. That Clause—
which makes federal law “the supreme Law of the Land . . . any
Thing in the Constitution or Laws of any State to the Contrary not
withstanding,” U. S. Const., Art. VI, cl. 2—cannot be read to permit
an approach to pre-emption that renders conflict pre-emption all but
meaningless. Here, it is enough to hold that when a party cannot
satisfy its state duties without the Federal Government’s special
permission and assistance, which is dependent on the exercise of
judgment by a federal agency, that party cannot independently sat
isfy those state duties for pre-emption purposes. Pp. 12–14, 17.
      (3) Wyeth is not to the contrary. The Court there held that a
4                       PLIVA, INC. v. MENSING

                                 Syllabus

    state tort action against a brand-name drug manufacturer for failure
    to provide an adequate warning label was not pre-empted because it
    was possible for the manufacturer to comply with both state and fed
    eral law under the FDA’s CBE 

–573.
    The federal statutes and regulations that apply to brand-name drug
    manufacturers differ, by Congress’ design, from those applicable to
    generic drug manufacturers. And different federal statutes and regu
    lations may, as here, lead to different pre-emption results. This
    Court will not distort the Supremacy Clause in order to create simi
    lar pre-emption across a dissimilar statutory scheme. Congress and
    the FDA retain authority to change the law and regulations if they so
    desire. Pp. 17–20.

   THOMAS, J., delivered the opinion of the Court, except as to Part III–
B–2. ROBERTS, C. J., and SCALIA and ALITO, JJ., joined that opinion in
full, and KENNEDY, J., joined as to all but Part III–B–2. SOTOMAYOR, J.,
filed a dissenting opinion, in which GINSBURG, BREYER, and KAGAN, JJ.,
joined.
                       Cite as: 564 U. S. ____ (2011)                              1

                            Opinion of the Court

    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash­
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.


SUPREME COURT OF THE UNITED STATES
                                  _________________

                   Nos. 09–993, 09–1039, and 09–1501
                                  _________________


             PLIVA, INC., ET AL., PETITIONERS
09–993                       v.
                    GLADYS MENSING

      ACTAVIS ELIZABETH, LLC, PETITIONER
09–1039               v.
               GLADYS MENSING

                 ACTAVIS, INC., PETITIONER
09–1501                      v.
                     JULIE DEMAHY
ON WRITS OF CERTIORARI TO THE UNITED STATES COURTS OF
     APPEALS FOR THE EIGHTH AND FIFTH CIRCUITS
                                [June 23, 2011]

  JUSTICE THOMAS delivered the opinion of the Court, ex­
cept as to Part III–B–2.*
  These consolidated lawsuits involve state tort-law
claims based on certain drug manufacturers’ alleged fail­
ure to provide adequate warning labels for generic meto­
clopramide. The question presented is whether federal
drug regulations applicable to generic drug manufacturers
directly conflict with, and thus pre-empt, these state-law
claims. We hold that they do.

——————
 * JUSTICE KENNEDY joins all but Part III–B–2 of this opinion.
2                  PLIVA, INC. v. MENSING 


                     Opinion of the Court 


                              I

   Metoclopramide is a drug designed to speed the move­
ment of food through the digestive system. The Food and
Drug Administration (FDA) first approved metoclopra­
mide tablets, under the brand name Reglan, in 1980. Five
years later, generic manufacturers also began producing meto­
clopramide. The drug is commonly used to treat diges-
tive tract problems such as diabetic gastroparesis and
gastroesophageal reflux disorder.
   Evidence has accumulated that long-term metoclopra­
mide use can cause tardive dyskinesia, a severe neurologi­
cal disorder. Studies have shown that up to 29% of pa­
tients who take metoclopramide for several years develop
this condition. McNeil v. Wyeth, 

, 370,
n. 5 (CA5 2006); see also Shaffer, Butterfield, Pamer, &
Mackey, Tardive Dyskinesia Risks and Metoclopramide
Use Before and After U. S. Market Withdrawal of Cis­
apride, 44 J. Am. Pharmacists Assn. 661, 663 (2004) (not­
ing 87 cases of metoclopramide-related tardive dyskinesia
reported to the FDA’s adverse event reporting system by
mid-2003).
   Accordingly, warning labels for the drug have been
strengthened and clarified several times. In 1985, the
label was modified to warn that “tardive dyskinesia . . .
may develop in patients treated with metoclopramide,”
and the drug’s package insert added that “[t]herapy longer
than 12 weeks has not been evaluated and cannot be
recommended.” Physician’s Desk Reference 1635–1636
(41st ed. 1987); see also Brief for Petitioner PLIVA et al.
21–22 (hereinafter PLIVA Brief). In 2004, the brand­
name Reglan manufacturer requested, and the FDA ap­
proved, a label change to add that “[t]herapy should not
exceed 12 weeks in duration.” Brief for United States as
Amicus Curiae 8 (hereinafter U. S. Brief). And in 2009,
the FDA ordered a black box warning—its strongest—
which states: “Treatment with metoclopramide can cause
                 Cite as: 564 U. S. ____ (2011)          3

                     Opinion of the Court

tardive dyskinesia, a serious movement disorder that is
often irreversible. . . . Treatment with metoclopramide
for longer than 12 weeks should be avoided in all but rare
cases.” See Physician’s Desk Reference 2902 (65th ed.
2011).
  Gladys Mensing and Julie Demahy, the plaintiffs in
these consolidated cases, were prescribed Reglan in 2001
and 2002, respectively. Both received generic metoclo­
pramide from their pharmacists. After taking the drug
as prescribed for several years, both women developed
tardive dyskinesia.
  In separate suits, Mensing and Demahy sued the ge­
neric drug manufacturers that produced the metoclopra­
mide they took (Manufacturers). Each alleged, as relevant
here, that long-term metoclopramide use caused her tar­
dive dyskinesia and that the Manufacturers were liable
under state tort law (specifically, that of Minnesota and
Louisiana) for failing to provide adequate warning labels.
They claimed that “despite mounting evidence that long
term metoclopramide use carries a risk of tardive dyskine­
sia far greater than that indicated on the label,” none of
the Manufacturers had changed their labels to adequately
warn of that danger. Mensing v. Wyeth, Inc., 

, 605 (CA8 2009); see also Demahy v. Actavis, Inc., 

, 430 (CA5 2010).
  In both suits, the Manufacturers urged that federal law
pre-empted the state tort claims. According to the Manu­
facturers, federal statutes and FDA regulations required
them to use the same safety and efficacy labeling as their
brand-name counterparts. This means, they argued, that
it was impossible to simultaneously comply with both
federal law and any state tort-law duty that required them
to use a different label.
  The Courts of Appeals for the Fifth and Eighth Circuits
rejected the Manufacturers’ arguments and held that Men­
sing and Demahy’s claims were not pre-empted. See
4                 PLIVA, INC. v. MENSING

                     Opinion of the 

; 593 F. 3d, at 449. We granted certiorari,
562 U. S. ___ (2010), consolidated the cases, and now
reverse each.
                             II
  Pre-emption analysis requires us to compare federal and
state law. We therefore begin by identifying the state tort
duties and federal labeling requirements applicable to the
Manufacturers.
                             A
   It is undisputed that Minnesota and Louisiana tort law
require a drug manufacturer that is or should be aware of
its product’s danger to label that product in a way that
renders it reasonably safe. Under Minnesota law, which
applies to Mensing’s lawsuit, “where the manufacturer . . .
of a product has actual or constructive knowledge of
danger to users, the . . . manufacturer has a duty to give
warning of such dangers.” Frey v. Montgomery Ward &
Co., 

, 788 (Minn. 1977). Similarly, under
Louisiana law applicable to Demahy’s lawsuit, “a manu­
facturer’s duty to warn includes a duty to provide ade­
quate instructions for safe use of a product.” Stahl v.
Novartis Pharmaceuticals Corp., 

, 269–270
(CA5 2002); see also La. Rev. Stat. Ann. §9:2800.57 (West
2009). In both States, a duty to warn falls specifically on
the manufacturer. See Marks v. OHMEDA, Inc., 2003–
1446, pp. 8–9 (La. App. 3/31/04), 

, 1155;
Gray v. Badger Min. Corp., 

, 274 (Minn.
2004).
   Mensing and Demahy have pleaded that the Manufac­
turers knew or should have known of the high risk of
tardive dyskinesia inherent in the long-term use of their
product. They have also pleaded that the Manufacturers
knew or should have known that their labels did not ade­
quately warn of that risk. App. 437–438, 67–69, 94–96.
                     Cite as: 564 U. S. ____ (2011)                   5

                         Opinion of the Court

The parties do not dispute that, if these allegations are
true, state law required the Manufacturers to use a differ­
ent, safer label.
                              B
  Federal law imposes far more complex drug labeling
requirements. We begin with what is not in dispute.
Under the 1962 Drug Amendments to the Federal Food,
Drug, and Cosmetic Act, 76 Stat. 780, 

. §301 et
seq., a manufacturer seeking federal approval to market a
new drug must prove that it is safe and effective and that
the proposed label is accurate and adequate.1 See, e.g.,

. §§355(b)(1), (d); Wyeth v. Levine, 

,
567 (2009). Meeting those requirements involves costly
and lengthy clinical testing. §§355(b)(1)(A), (d); see also D.
Beers, Generic and Innovator Drugs: A Guide to FDA
Approval Requirements §2.02[A] (7th ed. 2008).
  Originally, the same rules applied to all drugs. In 1984,
however, Congress passed the Drug Price Competition and
Patent Term Restoration Act, 98 Stat. 1585, commonly
called the Hatch-Waxman Amendments. Under this law,
“generic drugs” can gain FDA approval simply by showing
equivalence to a reference listed drug that has already
been approved by the FDA.2 

. §355(j)(2)(A).
This allows manufacturers to develop generic drugs in­
expensively, without duplicating the clinical trials already
performed on the equivalent brand-name drug. A generic
drug application must also “show that the [safety and
——————
  1 All relevant events in these cases predate the Food and Drug

Administration Amendments Act of 2007, 121 Stat. 823. We therefore
refer exclusively to the pre-2007 statutes and regulations and express
no view on the impact of the 2007 Act.
  2 As we use it here, “generic drug” refers to a drug designed to be a

copy of a reference listed drug (typically a brand-name drug), and thus
identical in active ingredients, safety, and efficacy. See, e.g., United
States v. Generix Drug Corp., 

, 454–455 (1983); 21 CFR
§314.3(b) (2006) (defining “reference listed drug”).
6                      PLIVA, INC. v. MENSING

                          Opinion of the Court

efficacy] labeling proposed . . . is the same as the labeling
approved for the [brand-name] drug.” §355(j)(2)(A)(v); see
also §355(j)(4)(G); Beers §§3.01, 3.03[A].
  As a result, brand-name and generic drug manufactur­
ers have different federal drug labeling duties. A brand­
name manufacturer seeking new drug approval is respon­
sible for the accuracy and adequacy of its label. See, e.g.,

. §§355(b)(1), (d); 

–571. A
manufacturer seeking generic drug approval, on the other
hand, is responsible for ensuring that its warning label is
the same as the brand name’s. See, e.g., §355(j)(2)(A)(v);
§355(j)(4)(G); 21 CFR §§314.94(a)(8), 314.127(a)(7).
  The parties do not disagree. What is in dispute is
whether, and to what extent, generic manufacturers may
change their labels after initial FDA approval. Mensing
and Demahy contend that federal law provided several
avenues through which the Manufacturers could have
altered their metoclopramide labels in time to prevent the
injuries here. The FDA, however, tells us that it inter­
prets its regulations to require that the warning labels of a
brand-name drug and its generic copy must always be the
same—thus, generic drug manufacturers have an ongoing
federal duty of “sameness.” U. S. Brief 16; see also 57 Fed.
Reg. 17961 (1992) (“[T]he [generic drug’s] labeling must
be the same as the listed drug product’s labeling because
the listed drug product is the basis for [generic drug] ap­
proval”). The FDA’s views are “controlling unless plainly
erroneous or inconsistent with the regulation[s]” or there
is any other reason to doubt that they reflect the FDA’s
fair and considered judgment. Auer v. Robbins, 

, 461, 462 (1997) (internal quotation marks omitted).3
——————
  3 The brief filed by the United States represents the views of the FDA.

Cf. Talk America, Inc. v. Michigan Bell Telephone Co., 564 U. S. ___,
___, n. 1 (2011) (slip op., at 1, n. 1); Chase Bank USA, N. A. v. McCoy,
562 U. S. ___, ___ (2011) (slip op., at 8). Although we defer to the
agency’s interpretation of its regulations, we do not defer to an agency’s
                   Cite as: 564 U. S. ____ (2011)               7

                       Opinion of the Court

                              1
   First, Mensing and Demahy urge that the FDA’s
“changes-being-effected” (CBE) process allowed the Manu­
facturers to change their labels when necessary. See Brief
for Respondents 33–35; see 

–444;
Gaeta v. Perrigo Pharmaceuticals Co., 

,
1231 (CA9 2011); Foster v. American Home Prods. Corp.,

, 170 (CA4 1994). The CBE process permits
drug manufacturers to “add or strengthen a contraindica­
tion, warning, [or] precaution,” 21 CFR §314.70(c)(6)(iii)(A)
(2006), or to “add or strengthen an instruction about dos­
age and administration that is intended to increase the
safe use of the drug product,” §314.70(c)(6)(iii)(C). When
making labeling changes using the CBE process, drug man­
ufacturers need not wait for preapproval by the FDA,
which ordinarily is necessary to change a label. 

. They need only simultaneously file a sup­
plemental application with the FDA. 21 CFR §314.70(c)(6).
   The FDA denies that the Manufacturers could have
used the CBE process to unilaterally strengthen their
warning labels. The agency interprets the CBE regulation
to allow changes to generic drug labels only when a ge­
neric drug manufacturer changes its label to match an
updated brand-name label or to follow the FDA’s instruc­
tions. U. S. Brief 15, 16, n. 7 (interpreting 21 CFR
§314.94(a)(8)(iv)); U. S. Brief 16, n. 8. The FDA argues
that CBE changes unilaterally made to strengthen a
generic drug’s warning label would violate the statutes
and regulations requiring a generic drug’s label to match
its brand-name counterpart’s. 

see also

. §355(j)(4)(G); 21 CFR §§314.94(a)(8)(iii),
314.150(b)(10) (approval may be withdrawn if the generic
drug’s label “is no longer consistent with that for [the
—————— 

ultimate conclusion about whether state law should be pre-empted.

Wyeth v. Levine, 

, 576 (2009).

8                 PLIVA, INC. v. MENSING

                     Opinion of the Court

brand-name]”).
  We defer to the FDA’s interpretation of its CBE and
generic labeling regulations.     Although Mensing and
Demahy offer other ways to interpret the regulations, see
Brief for Respondents 33–35, we do not find the agency’s
interpretation “plainly erroneous or inconsistent with the
regulation.” 

(internal quotation marks
omitted). Nor do Mensing and Demahy suggest there is
any other reason to doubt the agency’s reading. We there­
fore conclude that the CBE process was not open to the
Manufacturers for the sort of change required by state
law.
                              2
   Next, Mensing and Demahy contend that the Manufac­
turers could have used “Dear Doctor” letters to send ad­
ditional warnings to prescribing physicians and other
healthcare professionals. See Brief for Respondents 36; 21
CFR §200.5. Again, the FDA disagrees, and we defer to
the agency’s views.
   The FDA argues that Dear Doctor letters qualify as
“labeling.” U. S. Brief 18; see also 

. §321(m); 21
CFR §202.1(l)(2). Thus, any such letters must be “consis­
tent with and not contrary to [the drug’s] approved . . .
labeling.” 21 CFR §201.100(d)(1). A Dear Doctor letter
that contained substantial new warning information
would not be consistent with the drug’s approved labeling.
Moreover, if generic drug manufacturers, but not the
brand-name manufacturer, sent such letters, that would
inaccurately imply a therapeutic difference between the
brand and generic drugs and thus could be impermissibly
“misleading.” U. S. Brief 19; see 21 CFR §314.150(b)(3)
(FDA may withdraw approval of a generic drug if “the
labeling of the drug . . . is false or misleading in any
particular”).
   As with the CBE regulation, we defer to the FDA.
                  Cite as: 564 U. S. ____ (2011)              9

                      Opinion of the Court

Mensing and Demahy offer no argument that the FDA’s
interpretation is plainly erroneous. See 

. Accordingly, we conclude that federal law did not
permit the Manufacturers to issue additional warnings
through Dear Doctor letters.
                              3
   Though the FDA denies that the Manufacturers could
have used the CBE process or Dear Doctor letters to
strengthen their warning labels, the agency asserts that
a different avenue existed for changing generic drug la­
bels. According to the FDA, the Manufacturers could have
proposed—indeed, were required to propose—stronger
warning labels to the agency if they believed such warn­
ings were needed. U. S. Brief 20; 57 Fed. Reg. 17961. If
the FDA had agreed that a label change was necessary,
it would have worked with the brand-name manufacturer
to create a new label for both the brand-name and generic
drug. 

this duty to 

. §352(f)(2),
which provides that a drug is “misbranded . . . [u]nless its
labeling bears . . . adequate warnings against . . . unsafe
dosage or methods or duration of administration or appli­
cation, in such manner and form, as are necessary for the
protection of users.” See U. S. Brief 12. By regulation, the
FDA has interpreted that statute to require that “labeling
shall be revised to include a warning as soon as there is
reasonable evidence of an association of a serious hazard
with a drug.” 21 CFR §201.57(e).
   According to the FDA, these requirements apply to ge­
neric drugs. As it explains, a “ ‘central premise of fed-
eral drug regulation is that the manufacturer bears re­
sponsibility for the content of its label at all times.’ ” U. S.
Brief 12–13 (quoting 

–571). The
FDA reconciles this duty to have adequate and accurate
labeling with the duty of sameness in the following way:
10                PLIVA, INC. v. MENSING

                     Opinion of the Court

Generic drug manufacturers that become aware of safety
problems must ask the agency to work toward strengthen­
ing the label that applies to both the generic and brand­
name equivalent drug. U. S. Brief 20.
  The Manufacturers and the FDA disagree over whether
this alleged duty to request a strengthened label actually
existed. The FDA argues that it explained this duty in the
preamble to its 1992 regulations implementing the Hatch-
Waxman Amendments. Ibid.; see 57 Fed. Reg. 17961 (“If
a [generic drug manufacturer] believes new safety infor­
mation should be added to a product’s labeling, it should
contact FDA, and FDA will determine whether the label­
ing for the generic and listed drugs should be revised”).
The Manufacturers claim that the FDA’s 19-year-old
statement did not create a duty, and that there is no evi­
dence of any generic drug manufacturer ever acting pur­
suant to any such duty. See Tr. of Oral Arg. 19–24;
Reply Brief for Petitioner PLIVA et al. 18–22. Because we
ultimately find pre-emption even assuming such a duty
existed, we do not resolve the matter.
                             C
  To summarize, the relevant state and federal require­
ments are these: State tort law places a duty directly on
all drug manufacturers to adequately and safely label
their products. Taking Mensing and Demahy’s allegations
as true, this duty required the Manufacturers to use a
different, stronger label than the label they actually used.
Federal drug regulations, as interpreted by the FDA,
prevented the Manufacturers from independently chang­
ing their generic drugs’ safety labels. But, we assume,
federal law also required the Manufacturers to ask for
FDA assistance in convincing the brand-name manufac­
turer to adopt a stronger label, so that all corresponding
generic drug manufacturers could do so as well. We turn
now to the question of pre-emption.
                    Cite as: 564 U. S. ____ (2011) 
                11

                         Opinion of the Court 


                            III

  The Supremacy Clause establishes that federal law
“shall be the supreme Law of the Land . . . any Thing
in the Constitution or Laws of any State to the Contrary
notwithstanding.” U. S. Const., Art. VI, cl. 2. Where state
and federal law “directly conflict,” state law must give
way. 

(THOMAS, J., concurring in
judgment); see also Crosby v. National Foreign Trade
Council, 

, 372 (2000) (“[S]tate law is natu­
rally preempted to the extent of any conflict with a federal
statute”). We have held that state and federal law conflict
where it is “impossible for a private party to comply with
both state and federal requirements.”4 Freightliner Corp.
v. Myrick, 

, 287 (1995) (internal quotation
marks omitted).5
                            A
  We find impossibility here. It was not lawful under
federal law for the Manufacturers to do what state law
required of them. And even if they had fulfilled their
federal duty to ask for FDA assistance, they would not
have satisfied the requirements of state law.
  If the Manufacturers had independently changed their
——————
  4 We do not address whether state and federal law “directly conflict”

in circumstances beyond “impossibility.” See 

,
590–591 (THOMAS, J., concurring in judgment) (suggesting that they
might).
  5 The Hatch-Waxman Amendments contain no provision expressly

pre-empting state tort claims. See post, at 9, 19 (SOTOMAYOR, J.,
dissenting). Nor do they contain any saving clause to expressly pre­
serve state tort claims. Cf. Williamson v. Mazda Motor of America,
Inc., 562 U. S. ___, ___ (2011) (THOMAS, J., concurring in judgment)
(discussing the saving clause in the National Traffic and Motor Vehicle
Safety Act of 1966, 

. §30103(e)). Although an express state­
ment on pre-emption is always preferable, the lack of such a statement
does not end our inquiry. Contrary to the dissent’s suggestion, the
absence of express pre-emption is not a reason to find no conflict pre­
emption. See post, at 19.
12                PLIVA, INC. v. MENSING

                     Opinion of the Court

labels to satisfy their state-law duty, they would have
violated federal law. Taking Mensing and Demahy’s
allegations as true, state law imposed on the Manufac­
turers a duty to attach a safer label to their generic meto­
clopramide. Federal law, however, demanded that ge­
neric drug labels be the same at all times as the corres­
ponding brand-name drug labels. See, e.g., 21 CFR
§314.150(b)(10). Thus, it was impossible for the Manufac­
turers to comply with both their state-law duty to change
the label and their federal law duty to keep the label the
same.
  The federal duty to ask the FDA for help in strengthen­
ing the corresponding brand-name label, assuming such
a duty exists, does not change this analysis. Although
requesting FDA assistance would have satisfied the Man­
ufacturers’ federal duty, it would not have satisfied
their state tort-law duty to provide adequate labeling.
State law demanded a safer label; it did not instruct the
Manufacturers to communicate with the FDA about the
possibility of a safer label. Indeed, Mensing and Demahy
deny that their state tort claims are based on the Manu­
facturers’ alleged failure to ask the FDA for assistance in
changing the labels. Brief for Respondents 53–54; cf.
Buckman Co. v. Plaintiffs’ Legal Comm., 

(2001) (holding that federal drug and medical device laws
pre-empted a state tort-law claim based on failure to
properly communicate with the FDA).
                            B
                            1
  Mensing and Demahy contend that, while their state­
law claims do not turn on whether the Manufacturers
asked the FDA for assistance in changing their labels, the
Manufacturers’ federal affirmative defense of pre-emption
does. Mensing and Demahy argue that if the Manufactur­
ers had asked the FDA for help in changing the corre­
                 Cite as: 564 U. S. ____ (2011)          13

                     Opinion of the Court

sponding brand-name label, they might eventually have
been able to accomplish under federal law what state law
requires. That is true enough. The Manufacturers “freely
concede” that they could have asked the FDA for help.
PLIVA Brief 48. If they had done so, and if the FDA
decided there was sufficient supporting information, and
if the FDA undertook negotiations with the brand-name
manufacturer, and if adequate label changes were decided
on and implemented, then the Manufacturers would have
started a Mouse Trap game that eventually led to a better
label on generic metoclopramide.
   This raises the novel question whether conflict pre­
emption should take into account these possible actions by
the FDA and the brand-name manufacturer. Here, what
federal law permitted the Manufacturers to do could have
changed, even absent a change in the law itself, depending
on the actions of the FDA and the brand-name manufac­
turer. Federal law does not dictate the text of each ge­
neric drug’s label, but rather ties those labels to their
brand-name counterparts. Thus, federal law would permit
the Manufacturers to comply with the state labeling re­
quirements if, and only if, the FDA and the brand-name
manufacturer changed the brand-name label to do so.
   Mensing and Demahy assert that when a private party’s
ability to comply with state law depends on approval and
assistance from the FDA, proving pre-emption requires
that party to demonstrate that the FDA would not have
allowed compliance with state law. Here, they argue, the
Manufacturers cannot bear their burden of proving impos­
sibility because they did not even try to start the process
that might ultimately have allowed them to use a safer
label. Brief for Respondents 47. This is a fair argument,
but we reject it.
   The question for “impossibility” is whether the private
party could independently do under federal law what state
law requires of it. See 

(finding
14                    PLIVA, INC. v. MENSING

                         Opinion of the Court

no pre-emption where the defendant could “unilaterally”
do what state law required). Accepting Mensing and
Demahy’s argument would render conflict pre-emption
largely meaningless because it would make most conflicts
between state and federal law illusory. We can often
imagine that a third party or the Federal Government
might do something that makes it lawful for a private
party to accomplish under federal law what state law
requires of it. In these cases, it is certainly possible that,
had the Manufacturers asked the FDA for help, they
might have eventually been able to strengthen their warn­
ing label. Of course, it is also possible that the Manufac­
turers could have convinced the FDA to reinterpret its
regulations in a manner that would have opened the CBE
process to them. Following Mensing and Demahy’s argu­
ment to its logical conclusion, it is also possible that,
by asking, the Manufacturers could have persuaded the
FDA to rewrite its generic drug regulations entirely or
talked Congress into amending the Hatch-Waxman
Amendments.
  If these conjectures suffice to prevent federal and state
law from conflicting for Supremacy Clause purposes, it
is unclear when, outside of express pre-emption, the Su­
premacy Clause would have any force.6 We do not read
the Supremacy Clause to permit an approach to pre­
emption that renders conflict pre-emption all but mean­
ingless. The Supremacy Clause, on its face, makes federal
law “the supreme Law of the Land” even absent an ex­
press statement by Congress. U. S. Const., Art. VI, cl. 2.
——————
  6 The dissent asserts that we are forgetting “purposes-and-objectives”

pre-emption. Post, at 15–16. But as the dissent acknowledges, pur­
poses-and-objectives pre-emption is a form of conflict pre-emption.
Post, at 9, 16. If conflict pre-emption analysis must take into account
hypothetical federal action, including possible changes in Acts of
Congress, then there is little reason to think that pre-emption based on
the purposes and objectives of Congress would survive either.
                 Cite as: 564 U. S. ____ (2011)          15

                    Opinion of the Court
                    Opinion of THOMAS, J.

                             2
   Moreover, the text of the Clause—that federal law shall
be supreme, “any Thing in the Constitution or Laws of any
State to the Contrary notwithstanding”—plainly contem­
plates conflict pre-emption by describing federal law as
effectively repealing contrary state law. Ibid.; see Nelson,
Preemption, 

. Rev. 225, 234 (2000); 

(describing discussion of the Supremacy Clause in state
ratification debates as concerning whether federal law
could repeal state law, or vice versa). The phrase “any
[state law] to the Contrary notwithstanding” is a non ob
stante provision. 

nn. 43–45. Eighteenth­
century legislatures used non obstante provisions to
specify the degree to which a new statute was meant to
repeal older, potentially conflicting statutes in the same
field. 

(citing dozens of statutes from the
1770’s and 1780’s with similar provisions). A non obstante
provision “in a new statute acknowledged that the statute
might contradict prior law and instructed courts not to
apply the general presumption against implied repeals.”

4 M. Bacon, A New Abridgment of the
Law 639 (4th ed. 1778) (“Although two Acts of Parliament
are seemingly repugnant, yet if there be no Clause of non
Obstante in the latter, they shall if possible have such
Construction, that the latter may not be a Repeal of the
former by Implication”). The non obstante provision in the
Supremacy Clause therefore suggests that federal law
should be understood to impliedly repeal conflicting state
law.
   Further, the provision suggests that courts should not
strain to find ways to reconcile federal law with seemingly
conflicting state law. Traditionally, courts went to great
lengths attempting to harmonize conflicting statutes, in
order to avoid implied repeals. Warder v. Arell, 

,
296 (1796) (opinion of Roane, J.) (“[W]e ought to seek for
such a construction as will reconcile [the statutes] to­
16                 PLIVA, INC. v. MENSING

                     Opinion of the Court
                     Opinion of THOMAS, J.

gether”); Ludlow’s Heirs v. Johnston, 

, 564
(1828) (“[I]f by any fair course of reasoning the two [stat­
utes] can be reconciled, both shall stand”); Doolittle v.
Bryan, 

, 566 (1853) (requiring “the repug­
nance be quite plain” before finding implied repeal). A
non obstante provision thus was a useful way for legisla­
tures to specify that they did not want courts distorting
the new law to accommodate the old. 

–242; see also J. Sutherland, Statutes and Statutory
Construction §147, p. 199 (1891) (“[W]hen there is inserted
in a statute a provision [of non obstante] . . . . It is to be
supposed that courts will be less inclined against recogniz­
ing repugnancy in applying such statutes”); Weston’s Case,
73 Eng. Rep. 780, 781 (K. B. 1576) (“[W]hen there are two
statutes, one in appearance crossing the other, and no
clause of non obstante is contained in the second statute
. . . the exposition ought to be that both should stand in
force”); G. Jacob, A New Law Dictionary (J. Morgan ed.,
10th ed. 1782) (definition of “statute,” ¶6: “[W]hen there is
a seeming variance between two statutes, and no clause of
non obstante in the latter, such construction shall be made
that both may stand”). The non obstante provision of
he Supremacy Clause indicates that a court need look no
further than “the ordinary meanin[g]” of federal law, and
should not distort federal law to accommodate conflicting
state law. 

(THOMAS, J., concur­
ring in judgment) (internal quotation marks omitted).
    To consider in our pre-emption analysis the contingen­
cies inherent in these cases—in which the Manufacturers’
ability to comply with state law depended on uncertain
federal agency and third-party decisions—would be incon­
sistent with the non obstante provision of the Supremacy
Clause. The Manufacturers would be required continually
to prove the counterfactual conduct of the FDA and brand­
name manufacturer in order to establish the supremacy of
federal law. We do not think the Supremacy Clause con­
                 Cite as: 564 U. S. ____ (2011)           17

                     Opinion of the Court

templates that sort of contingent supremacy. The non
obstante provision suggests that pre-emption analysis
should not involve speculation about ways in which fed­
eral agency and third-party actions could potentially
reconcile federal duties with conflicting state duties.
When the “ordinary meaning” of federal law blocks a
private party from independently accomplishing what
state law requires, that party has established pre-emption.
                              3
   To be sure, whether a private party can act sufficiently
independently under federal law to do what state law
requires may sometimes be difficult to determine. But this
is not such a case. Before the Manufacturers could satisfy
state law, the FDA—a federal agency—had to undertake
special effort permitting them to do so. To decide these
cases, it is enough to hold that when a party cannot satisfy
its state duties without the Federal Government’s special
permission and assistance, which is dependent on the
exercise of judgment by a federal agency, that party can­
not independently satisfy those state duties for pre­
emption purposes.
   Here, state law imposed a duty on the Manufacturers to
take a certain action, and federal law barred them from
taking that action. The only action the Manufacturers
could independently take—asking for the FDA’s help—is
not a matter of state-law concern. Mensing and Demahy’s
tort claims are pre-empted.
                             C
  Wyeth is not to the contrary. In that case, as here,
the plaintiff contended that a drug manufacturer had
breached a state tort-law duty to provide an adequate
warning 

–560. The Court held that
the lawsuit was not pre-empted because it was possible for
Wyeth, a brand-name drug manufacturer, to comply with
18                     PLIVA, INC. v. MENSING

                          Opinion of the Court

both state and federal law. 

Specifically,
the CBE regulation, 21 CFR §314.70(c)(6)(iii), permitted a
brand-name drug manufacturer like Wyeth “to unilater­
ally strengthen its warning” without prior FDA 

; 

–8. Thus, the federal
regulations applicable to Wyeth allowed the company, of
its own volition, to strengthen its label in compliance with
its state tort duty.8
   We recognize that from the perspective of Mensing and
Demahy, finding pre-emption here but not in Wyeth makes
little sense. Had Mensing and Demahy taken Reglan, the
brand-name drug prescribed by their doctors, Wyeth would
control and their lawsuits would not be pre-empted. But

——————
   7 Wyeth also urged that state tort law “creat[ed] an unacceptable

‘obstacle to the accomplishment and execution of the full purposes
and objectives of Congress.’ 

–564 (quoting Hines v.
Davidowitz, 

, 67 (1941)). The Court rejected that argu­
ment, and that type of pre-emption is not argued here. Cf. post, at 16,
n. 13 (opinion of SOTOMAYOR, J.).
   8 The FDA, however, retained the authority to eventually rescind

Wyeth’s unilateral CBE changes. Accordingly, the Court noted that
Wyeth could have attempted to show, by “clear evidence,” that the FDA
would have rescinded any change in the label and thereby demonstrate
that it would in fact have been impossible to do under federal law
what state law required. 

. Wyeth offered no such
evidence.
   That analysis is consistent with our holding today. The Court in
Wyeth asked what the drug manufacturer could independently do under
federal law, and in the absence of clear evidence that Wyeth could not
have accomplished what state law required of it, found no pre-emption.
The Wyeth Court held that, because federal law accommodated state
law duties, “the possibility of impossibility” was “not enough.” Post, at
10; see also Rice v. Norman Williams Co., 

, 659 (1982)
(rejecting “hypothetical” impossibility). But here, “existing” federal law
directly conflicts with state law. Post, at 15 (“Conflict analysis neces­
sarily turns on existing law”). The question in these cases is not
whether the possibility of impossibility establishes pre-emption, but
rather whether the possibility of possibility defeats pre-emption. Post,
at 10.
                     Cite as: 564 U. S. ____ (2011)                   19

                          Opinion of the Court

because pharmacists, acting in full accord with state law,
substituted generic metoclopramide instead, federal law
pre-empts these lawsuits. See, e.g., Minn. Stat. §151.21
(2010) (describing when pharmacists may substitute ge­
neric drugs); La. Rev. Stat. Ann. §37:1241(A)(17) (West
2007) (same). We acknowledge the unfortunate hand that
federal drug regulation has dealt Mensing, Demahy, and
others similarly situated.9
  But “it is not this Court’s task to decide whether the
statutory scheme established by Congress is unusual or
even bizarre.” Cuomo v. Clearing House Assn., L. L. C.,
557 U. S. ___, ___ (2009) (THOMAS, J., concurring in part
and dissenting in part) (slip op., at 21) (internal quotation
marks and brackets omitted). It is beyond dispute that
the federal statutes and regulations that apply to brand­
name drug manufacturers are meaningfully different than
those that apply to generic drug manufacturers. Indeed, it
is the special, and different, regulation of generic drugs
that allowed the generic drug market to expand, bringing
more drugs more quickly and cheaply to the public. But
different federal statutes and regulations may, as here,
lead to different pre-emption results. We will not distort
the Supremacy Clause in order to create similar pre­
emption across a dissimilar statutory scheme. As always,
Congress and the FDA retain the authority to change the
——————
   9 That said, the dissent overstates what it characterizes as the “many

absurd consequences” of our holding. Post, at 18. First, the FDA in­
forms us that “[a]s a practical matter, genuinely new information about
drugs in long use (as generic drugs typically are) appears infre­
quently.” U. S. Brief 34–35. That is because patent protections ordi­
narily prevent generic drugs from arriving on the market for a number
of years after the brand-name drug appears. Indeed, situations like the
one alleged here are apparently so rare that the FDA has no “formal
regulation” establishing generic drug manufacturers’ duty to initiate a
label change, nor does it have any regulation setting out that label­
change process. 

Second, the dissent admits that, even
under its approach, generic drug manufacturers could establish pre­
emption in a number of scenarios. Post, at 12–13.
20                 PLIVA, INC. v. MENSING

                     Opinion of the Court

law and regulations if they so desire.
                        *     *    *
  The judgments of the Fifth and Eighth Circuits are
reversed, and the cases are remanded for further proceed­
ings consistent with this opinion.
                                          It is so ordered.
                 Cite as: 564 U. S. ____ (2011)           1

                  SOTOMAYOR, J., dissenting

SUPREME COURT OF THE UNITED STATES
                         _________________

              Nos. 09–993, 09–1039, and 09–1501
                         _________________


          PLIVA, INC., ET AL., PETITIONERS
09–993                    v.
                 GLADYS MENSING

      ACTAVIS ELIZABETH, LLC, PETITIONER
09–1039               v.
               GLADYS MENSING

             ACTAVIS, INC., PETITIONER
09–1501                  v.
                 JULIE DEMAHY
ON WRITS OF CERTIORARI TO THE UNITED STATES COURTS OF
     APPEALS FOR THE EIGHTH AND FIFTH CIRCUITS
                        [June 23, 2011]

  JUSTICE SOTOMAYOR, with whom JUSTICE GINSBURG,
JUSTICE BREYER, and JUSTICE KAGAN join, dissenting.
  The Court today invokes the doctrine of impossibility
pre-emption to hold that federal law immunizes generic
drug manufacturers from all state-law failure-to-warn
claims because they cannot unilaterally change their la
bels. I cannot agree. We have traditionally held defen
dants claiming impossibility to a demanding standard:
Until today, the mere possibility of impossibility had not
been enough to establish pre-emption.
  The Food and Drug Administration (FDA) permits—
and, the Court assumes, requires—generic-drug manufac
turers to propose a label change to the FDA when they
believe that their labels are inadequate. If it agrees that
the labels are inadequate, the FDA can initiate a change
2                 PLIVA, INC. v. MENSING

                   SOTOMAYOR, J., dissenting

to the brand-name label, triggering a corresponding
change to the generic labels. Once that occurs, a generic
manufacturer is in full compliance with both federal law
and a state-law duty to warn. Although generic manufac
turers may be able to show impossibility in some cases,
petitioners, generic manufacturers of metoclopramide
(Manufacturers), have shown only that they might have
been unable to comply with both federal law and their
state-law duties to warn respondents Gladys Mensing and
Julie Demahy. This, I would hold, is insufficient to sus
tain their burden.
   The Court strains to reach the opposite conclusion. It
invents new principles of pre-emption law out of thin air to
justify its dilution of the impossibility standard. It effec
tively rewrites our decision in Wyeth v. Levine, 

(2009), which holds that federal law does not pre-empt
failure-to-warn claims against brand-name drug manufac
turers. And a plurality of the Court tosses aside our re
peated admonition that courts should hesitate to conclude
that Congress intended to pre-empt state laws governing
health and safety. As a result of today’s decision, whether
a consumer harmed by inadequate warnings can obtain
relief turns solely on the happenstance of whether her
pharmacist filled her prescription with a brand-name or
generic drug. The Court gets one thing right: This out
come “makes little sense.” Ante, at 18.
                               I

                               A

    Today’s decision affects 75 percent of all prescription
drugs dispensed in this country. The dominant position of
generic drugs in the prescription drug market is the result
of a series of legislative measures, both federal and state.
   In 1984, Congress enacted the Drug Price Competi-
tion and Patent Term Restoration Act, 98 Stat. 1585—
commonly known as the Hatch-Waxman Amendments to
                    Cite as: 564 U. S. ____ (2011)                  3

                      SOTOMAYOR, J., dissenting

the Federal Food, Drug, and Cosmetic Act (FDCA)—to
“make available more low cost generic drugs by establish
ing a generic drug approval procedure,” H. R. Rep. No. 98–
857, pt. 1, p. 14 (1984). As the majority explains, to ac
complish this goal the amendments establish an abbrevi
ated application process for generic drugs. Ante, at 5–6;
see also 

. §355(j)(2)(A). The abbreviated ap
proval process implements the amendments’ core principle
that generic and brand-name drugs must be the “same” in
nearly all respects: To obtain FDA approval, a generic
manufacturer must ordinarily show, among other things,
that its product has the same active ingredients as an
approved brand-name drug; that “the route of adminis
tration, the dosage form, and the strength of the new
drug are the same” as the brand-name drug; and that its
product is “bioequivalent” to the brand-name drug.
§§355(j)(2)(A)(ii), (iii), (iv). By eliminating the need for
generic manufacturers to prove their drugs’ safety and
efficacy independently, the Hatch-Waxman Amendments
allow generic manufacturers to bring drugs to market
much less expensively.
  The States have also acted to expand consumption of
low-cost generic drugs. In the years leading up to passage
of the Hatch-Waxman Amendments, States enacted legis
lation authorizing pharmacists to substitute generic drugs
when filling prescriptions for brand-name drugs. Chris
tensen, Kirking, Ascione, Welage, & Gaither, Drug Prod
uct Selection: Legal Issues, 41 J. Am. Pharmaceutical
Assn. 868, 869 (2001). Currently, all States have some
form of generic substitution law. See 

generic substitution in certain circumstances.
Dept. of Health and Human Servs., ASPE Issue Brief:
Expanding the Use of Generic Drugs 7 (2010) (hereinafter
Expanding the Use of Generic Drugs);1 see, e.g., N. Y.
——————
 1 Online   at http://aspe.hhs.gov/sp/reports/2010/GenericDrugs/ib.pdf
4                     PLIVA, INC. v. MENSING

                      SOTOMAYOR, J., dissenting

Educ. Law Ann. §6816–a (West 2010). Others permit, but
do not require, substitution. Expanding the Use of Ge
neric Drugs 7; see, e.g., Cal. Bus. & Prof. Code Ann. §4073
(West Supp. 2011). Some States require patient consent to
substitution, and all States “allow the physician to specify
that the brand name must be prescribed, although with
different levels of effort from the physician.” Expanding
the Use of Generic Drugs 7.2
   These legislative efforts to expand production and con
sumption of generic drugs have proved wildly successful.
It is estimated that in 1984, when the Hatch-Waxman
Amendments were enacted, generic drugs constituted 19
percent of drugs sold in this country. Congressional Bud
get Office, How Increased Competition from Generic
Drugs Has Affected Prices and Returns in the Pharmaceu
tical Industry 27 (1998).3 Today, they dominate the mar
ket. See Expanding the Use of Generic Drugs 2 (generic
drugs constituted 75 percent of all dispensed prescription
drugs in 2009). Ninety percent of drugs for which a
generic version is available are now filled with generics.

In many cases, once generic versions of a
drug enter the market, the brand-name manufacturer stops
selling the brand-name drug altogether. See Brief for
Marc T. Law et al. as Amici Curiae 18 (citing studies
——————
(all Internet materials as visited June 17, 2011, and available in Clerk
of Court’s case file).
   2 In addition, many insurance plans are structured to promote generic

use. See Congressional Budget Office, Effects of Using Generic Drugs
on Medicare’s Prescription Drug Spending 9 (2010), online at http://
www.cbo.gov/ftpdoc/118xx/doc11838/09-15-PrescriptionDrugs.pdf.
State Medicaid programs similarly promote generic use. See Kaiser
Comm’n on Medicaid and the Uninsured, State Medicaid Outpatient
Prescription Drug Policies: Findings from a National Survey,
2005 Update 10 (2005), online at www.kff.org/medicaid/upload/state
medicaid-outpatient-prescription-drug-policies-findings-from-a-national
survey-2005-update-report.pdf.
   3 Online at http://www.cbo.gov/ftpdocs/6xx/doc655/pharm.pdf.
                     Cite as: 564 U. S. ____ (2011)                   5

                      SOTOMAYOR, J., dissenting

showing that anywhere from one-third to one-half of
generic drugs no longer have a marketed brand-name
equivalent). Reflecting the success of their products,
many generic manufacturers, including the Manufacturers
and their amici, are huge, multinational companies. In
total, generic drug manufacturers sold an estimated $66
billion of drugs in this country in 2009. See 

                             B
   As noted, to obtain FDA approval a generic manufac
turer must generally show that its drug is the same as an
approved brand-name drug. It need not conduct clinical
trials to prove the safety and efficacy of the drug. This
does not mean, however, that a generic manufacturer has
no duty under federal law to ensure the safety of its prod
ucts. The FDA has limited resources to conduct postap
proval monitoring of drug safety. See 

. Manufacturers, we have recognized, “have superior
access to information about their drugs, especially in the
postmarketing phase as new risks emerge.” 

579. Federal law thus obliges drug manufacturers—both
brand-name and generic—to monitor the safety of their
products.
   Under federal law, generic manufacturers must “develop
written procedures for the surveillance, receipt, evalua
tion, and reporting of postmarketing adverse drug experi
ences” to the FDA.4 21 CFR §314.80(b);5 see also §314.98
(making §314.80 applicable to generic manufacturers);
Brief for United States as Amicus Curiae 6, and n. 2
(hereinafter U. S. Brief). They must review all reports
of adverse drug experiences received from “any source.”
——————
  4 An adverse drug experience is defined as “[a]ny adverse event asso

ciated with the use of a drug in humans, whether or not considered
drug related.” 21 CFR §314.80(a) (2006).
  5 Like the majority, I refer to the pre-2007 statutes and regulations.

See ante, at 5, n. 1.
6                      PLIVA, INC. v. MENSING

                       SOTOMAYOR, J., dissenting

§314.80(b). If a manufacturer receives a report of a seri
ous and unexpected adverse drug experience, it must re
port the event to the FDA within 15 days and must
“promptly investigate.” §§314.80(c)(1)(i)–(ii); see also Tr.
of Oral Arg. 8. Most other adverse drug experiences must
be reported on a quarterly or yearly basis.6 §314.80(c)(2).
Generic manufacturers must also submit to the FDA an
annual report summarizing “significant new information
from the previous year that might affect the safety, ef
fectiveness, or labeling of the drug product,” including a
“description of actions the [manufacturer] has taken or
intends to take as a result of this new information.”
§314.81(b)(2)(i); see also §314.98(c).
   Generic manufacturers, the majority assumes, also bear
responsibility under federal law for monitoring the ade
quacy of their warnings. I agree with the majority’s con
clusion that generic manufacturers are not permitted
unilaterally to change their labels through the “changes
being-effected” (CBE) process or to issue additional warn
ings through “Dear Doctor” letters. See ante, at 6–9.
According to the FDA, however, that generic manufactur
——————
   6 At congressional hearings on the Hatch-Waxman Amendments,

representatives of the generic drug manufacturers confirmed both their
obligation and their ability to conduct postapproval investigation of
adverse drug experiences. See Drug Legislation: Hearings on H. R.
1554 et al. before the Subcommittee on Health and the Environment of
the House Committee on Energy and Commerce, 98th Cong., 1st Sess.,
45 (1983) (statement of Kenneth N. Larsen, chairman of the Generic
Pharmaceutical Industry Association (GPhA)) (generic manufacturers
“are sensitive to the importance of looking at adverse reactions”); 

(“[W]e will do and provide whatever is required to be performed
to meet the regulatory requirement to provide for the safety and well
being of those that are using the drug, this is our role and responsibil
ity. This is an obligation to be in this business”); 

(state
ment of Bill Haddad, executive officer and president of GPhA) (“Every
single generic drug company that I know has a large research staff. It
not only researches the drug that they are copying, or bringing into the
market but it researches new drugs, researches adverse reaction[s]”).
                     Cite as: 564 U. S. ____ (2011)                   7

                      SOTOMAYOR, J., dissenting

ers cannot disseminate additional warnings on their own
does not mean that federal law permits them to remain
idle when they conclude that their labeling is inadequate.
FDA regulations require that labeling “be revised to in
clude a warning as soon as there is reasonable evidence of
an association of a serious hazard with a drug.” 21 CFR
§201.57(e) (2006), currently codified at 21 CFR §201.80(e)
(2010); see also 

–571. The FDA
construes this regulation to oblige generic manufacturers
“to seek to revise their labeling and provide FDA with
supporting information about risks” when they believe that
additional warnings are necessary.7 U. S. Brief 20.
   The Manufacturers disagree. They read the FDA regu
lation to require them only to ensure that their labels
match the brand-name labels. See Brief for Petitioner
PLIVA et al. 38–41. I need not decide whether the regula
tion in fact obliges generic manufacturers to approach the
FDA to propose a label change. The majority assumes
that it does. And even if generic manufacturers do not
have a duty to propose label changes, two points remain
undisputed. First, they do have a duty under federal law
——————
   7 The FDA’s construction of this regulation mirrors the guidance it

provided to generic manufacturers nearly 20 years ago in announcing
the final rule implementing the abbreviated application process for
generic drugs:
“If an ANDA [i.e., application for approval of a generic drug] applicant
believes new safety information should be added to a product’s labeling,
it should contact FDA, and FDA will determine whether the labeling
for the generic and listed drugs should be revised. After approval of an
ANDA, if an ANDA holder believes that new safety information should
be added, it should provide adequate supporting information to FDA,
and FDA will determine whether the labeling for the generic and listed
drugs should be revised.” 57 Fed. Reg. 17961 (1992).
FDA’s internal procedures recognize that the Office of Generic Drugs
will have to consult with other FDA components on “some labeling
reviews.” Manual of Policies and Procedures 5200.6, p. 1 (May 9, 2001).
Consultations involving “possible serious safety concerns” receive the
highest priority. 

8                  PLIVA, INC. v. MENSING

                   SOTOMAYOR, J., dissenting

to monitor the safety of their products. And, second, they
may approach the FDA to propose a label change when
they believe a change is required.
                             II
  This brings me to the Manufacturers’ pre-emption de
fense. State law obliged the Manufacturers to warn of
dangers to users. See Hines v. Remington Arms Co., 94–
0455, p. 10 (La. 12/8/94), 

, 337; Frey v.
Montgomery Ward & Co., 

, 788 (Minn.
1977). The Manufacturers contend, and the majority
agrees, that federal law pre-empts respondents’ failure-to
warn claims because, under federal law, the Manufac
turers could not have provided additional warnings to
respondents without the exercise of judgment by the FDA.
I cannot endorse this novel conception of impossibility
pre-emption.
                               A
    Two principles guide all pre-emption analysis. First,
“ ‘the purpose of Congress is the ultimate touchstone in
every pre-emption case.’ ” 

(quoting
Medtronic, Inc. v. Lohr, 

, 485 (1996)). Sec
ond, “ ‘[i]n all pre-emption cases, and particularly in those
in which Congress has legislated . . . in a field which the
States have traditionally occupied, . . . we start with the
assumption that the historic police powers of the States
were not to be superseded by the Federal Act unless that
was the clear and manifest purpose of Congress.’ ” 

(quoting 

; some
internal quotation marks omitted; alterations in original).
    These principles find particular resonance in these
cases. The States have traditionally regulated health and
safety matters. See 

Notwithstanding Con
gress’ “certain awareness of the prevalence of state tort
litigation” against drug manufacturers, Wyeth, 555 U. S.,
                  Cite as: 564 U. S. ____ (2011)              9

                    SOTOMAYOR, J., dissenting

at 575, Congress has not expressly pre-empted state-law
tort actions against prescription drug manufacturers,
whether brand-name or generic. To the contrary, when
Congress amended the FDCA in 1962 to “enlarg[e] the
FDA’s powers to ‘protect the public health’ and ‘assure the
safety, effectiveness, and reliability of drugs,’ [it] took care
to preserve state law.” 

(quoting 76 Stat. 780);
see Pub. L. 87–781, §202, 76 Stat. 793 (“Nothing in the
amendments made by this Act to the [FDCA] shall be
construed as invalidating any provision of State law which
would be valid in the absence of such amendments un-
less there is a direct and positive conflict between such
amendments and such provision of State law”). Notably,
although Congress enacted an express pre-emption provi
sion for medical devices in 1976, see Pub. L. 94–295, §521,
90 Stat. 574, 

. §360k(a), it included no such
provision in the Hatch-Waxman Amendments eight years
later. Cf. 

, 574–575. Congress’
“silence on the issue . . . is powerful evidence that [it] did
not intend FDA oversight to be the exclusive means of
ensuring drug safety and effectiveness.” 

                              B
   Federal law impliedly pre-empts state law when state
and federal law “conflict”—i.e., when “it is impossible for a
private party to comply with both state and federal law” or
when state law “stands as an obstacle to the accomplish
ment and execution of the full purposes and objectives of
Congress.” Crosby v. National Foreign Trade Council, 

, 372–373 (2000) (internal quotation marks omit
ted). The Manufacturers rely solely on the former ground
of pre-emption.
   Impossibility pre-emption, we have emphasized, “is a de
manding defense.” 

. Because
pre-emption is an affirmative defense, a defendant seeking
to set aside state law bears the burden to prove impossibil
10                    PLIVA, INC. v. MENSING

                       SOTOMAYOR, J., dissenting

ity. See ibid.; Silkwood v. Kerr-McGee Corp., 

, 255 (1984). To prevail on this defense, a defendant
must demonstrate that “compliance with both federal and
state [law] is a physical impossibility.” Florida Lime &
Avocado Growers, Inc. v. Paul, 

, 142–143
(1963); see also 

. In other words,
there must be an “inevitable collision” between federal and
state law. Florida 

. “The existence
of a hypothetical or potential conflict is insufficient to
warrant” pre-emption of state law. Rice v. Norman Wil
liams Co., 

, 659 (1982); see also Gade v.
National Solid Wastes Management Assn., 

,
110 (1992) (KENNEDY, J., concurring in part and concur
ring in judgment). In other words, the mere possibility of
impossibility is not enough.
   The Manufacturers contend that it was impossible for
them to provide additional warnings to respondents Men
sing and Demahy because federal law prohibited them
from changing their labels unilaterally.8 They concede,
however, that they could have asked the FDA to initiate a
label change. If the FDA agreed that a label change was
required, it could have asked, and indeed pressured, the
brand-name manufacturer to change its label, triggering
a corresponding change to the Manufacturers’ generic la

——————
  8 In its decision below, the Eighth Circuit suggested that the Manu

facturers could not show impossibility because federal law merely
permitted them to sell generic drugs; it did not require them to do so.
See Mensing v. Wyeth, Inc., 

, 611 (2009) (“The generic
defendants were not compelled to market metoclopramide. If they
realized their label was insufficient but did not believe they could even
propose a label change, they could have simply stopped selling the
product”); see also Geier v. American Honda Motor Co., 

,
873 (2000) (describing “a case of impossibility” as one “in which state
law penalizes what federal law requires” (emphasis added)). Respon
dents have not advanced this argument, and I find it unnecessary to
consider.
                     Cite as: 564 U. S. ____ (2011)                   11

                       SOTOMAYOR, J., dissenting

bels.9 Thus, had the Manufacturers invoked the available
mechanism for initiating label changes, they may well
have been able to change their labels in sufficient time to
warn respondents. Having failed to do so, the Manufac
turers cannot sustain their burden (at least not without
further factual development) to demonstrate that it was
impossible for them to comply with both federal and state
law. At most, they have demonstrated only “a hypotheti
cal or potential conflict.” 

.
  Like the majority, the Manufacturers focus on the fact
that they cannot change their labels unilaterally—which
distinguishes them from the brand-name-manufacturer
defendant in Wyeth. They correctly point out that in
Wyeth we concluded that the FDA’s CBE regulation au
thorized the defendant to strengthen its warnings before
receiving agency approval of its supplemental application
describing the label 

–571; see
also 21 CFR §314.70(c)(6). But the defendant’s label
change was contingent on FDA acceptance, as the FDA
retained “authority to reject labeling changes made pur
suant to the CBE regulation.” 

.
Thus, in the long run, a brand-name manufacturer’s com
pliance with a state-law duty to warn required action by
two actors: The brand-name manufacturer had to change
the label and the FDA, upon reviewing the supplemental
application, had to agree with the change.10 The need for
——————
  9 At  the time respondents’ cause of action arose, the FDA did not have
authority to require a brand-name manufacturer to change its label.
(It received that authority in 2007. See Pub. L. 110–85, §901, 121
Stat. 924–926, 

. §355(o)(4) (2006 ed., Supp. III). It did, how
ever, have the equally significant authority to withdraw the brand-name
manufacturer’s permission to market its drug if the manufacturer
refused to make a requested labeling change. See 

. §355(e)
(2006 ed.); 21 CFR §314.150(b)(3).
   10 A brand-name manufacturer’s ability to comply with a state-law

duty to warn would depend on its own unilateral actions only during
the period after it should have changed its label but before the FDA
12                    PLIVA, INC. v. MENSING

                      SOTOMAYOR, J., dissenting

FDA approval of the label change did not make compliance
with federal and state law impossible in every case. In
stead, because the defendant bore the burden to show
impossibility, we required it to produce “clear evidence
that the FDA would not have approved a change to [the]
label.” 

the same approach in these cases. State
law, respondents allege, required the Manufacturers to
provide a strengthened warning about the dangers of
long-term metoclopramide use.11 Just like the brand-name
manufacturer in Wyeth, the Manufacturers had available
to them a mechanism for attempting to comply with their
state-law duty to warn. Federal law thus “accommodated”
the Manufacturers’ state-law duties. See ante, at 18, n. 8.
It was not necessarily impossible for the Manufacturers to
comply with both federal and state law because, had they
approached the FDA, the FDA may well have agreed that
a label change was necessary. Accordingly, as in Wyeth, I
would require the Manufacturers to show that the FDA
would not have approved a proposed label change. They
have not made such a showing: They do “not argue that
[they] attempted to give the kind of warning required by
[state law] but [were] prohibited from doing so by the
FDA.” 

.
   This is not to say that generic manufacturers could
never show impossibility. If a generic-manufacturer de
fendant proposed a label change to the FDA but the FDA
rejected the proposal, it would be impossible for that
defendant to comply with a state-law duty to warn. Like
wise, impossibility would be established if the FDA had
——————
would have approved or disapproved the label change. The claim in
Wyeth does not appear to have arisen during that period.
  11 Respondents’ state-law claim is not that the Manufacturers were

required to ask the FDA for assistance in changing the labels; the role
of the FDA arises only as a result of the Manufacturers’ pre-emption
defense.
                 Cite as: 564 U. S. ____ (2011)           13

                   SOTOMAYOR, J., dissenting

not yet responded to a generic manufacturer’s request for
a label change at the time a plaintiff’s injuries arose. A
generic manufacturer might also show that the FDA had
itself considered whether to request enhanced warnings in
light of the evidence on which a plaintiff’s claim rests but
had decided to leave the warnings as is. (The Manufac
turers make just such an argument in these cases. See,
e.g., Brief for Petitioner Actavis et al. 11.) But these are
questions of fact to be established through discovery.
Because the burden of proving impossibility falls on the
defendant, I would hold that federal law does not render
it impossible for generic manufacturers to comply with
a state-law duty to warn as a categorical matter.
   This conclusion flows naturally from the overarching prin
ciples governing our pre-emption doctrine. 

. Our “respect for the States as ‘independent sover
eigns in our federal system’ leads us to assume that ‘Con
gress does not cavalierly pre-empt state-law causes of
action.’ ” 

–566, n. 3 (quoting 

). It is for this reason that we hold defen
dants asserting impossibility to a “demanding” standard.

. This presumption against pre
emption has particular force when the Federal Govern
ment has afforded defendants a mechanism for complying
with state law, even when that mechanism requires fed
eral agency action. (The presumption has even greater
force when federal law requires defendants to invoke that
mechanism, as the majority assumes in these cases.) In
such circumstances, I would hold, defendants will usually
be unable to sustain their burden of showing impossibility
if they have not even attempted to employ that mecha
nism. Any other approach threatens to infringe the
States’ authority over traditional matters of state inter
est—such as the failure-to-warn claims here—when Con
gress expressed no intent to pre-empt state law.
14                  PLIVA, INC. v. MENSING

                     SOTOMAYOR, J., dissenting

                              C
  The majority concedes that the Manufacturers might
have been able to accomplish under federal law what state
law requires. Ante, at 12–13. To reach the conclusion that
the Manufacturers have nonetheless satisfied their bur
den to show impossibility, the majority invents a new pre
emption rule: “The question for ‘impossibility’ is whether
the private party could independently do under federal
law what state law requires of it.” Ante, at 13 (empha-
sis added). Because the Manufacturers could not have
changed their labels without the exercise of judgment by
the FDA, the majority holds, compliance with both state
and federal law was impossible in these cases.12
  The majority’s new test has no basis in our precedents.
The majority cites only Wyeth in support of its test. As
discussed above, however, Wyeth does not stand for the
proposition that it is impossible to comply with both fed
eral and state law whenever federal agency approval is
required. To the contrary, label changes by brand-name
manufacturers such as Wyeth are subject to FDA review
and acceptance. 

–12. And, even if Wyeth
could be characterized as turning on the fact that the
brand-name manufacturer could change its label unilater
ally, the possibility of unilateral action was, at most, a
sufficient condition for rejecting the impossibility defense
in that case. Wyeth did not hold that unilateral action is a
necessary condition in every case.
——————
  12 These cases do not involve a situation where a brand-name

manufacturer itself produces generic drugs. See Okie, Multinational
Medicines—Ensuring Drug Quality in an Era of Global Manufactur
ing, 361 N. Eng. J. Med. 737, 738 (2009); see also GPhA, Frequently
Asked Questions About Generics, http://www.gphaonline.org/about
gpha/about-generics/faq (“Brand-name companies make about half of
generic drugs”). In that case, the manufacturer could independently
change the brand-name label under the CBE regulation, triggering a
corresponding change to its own generic label.
                  Cite as: 564 U. S. ____ (2011)            15

                    SOTOMAYOR, J., dissenting

   With so little support in our case law, the majority un
derstandably turns to other rationales. None of the
rationales that it offers, however, makes any sense. First,
it offers a reductio ad absurdum: If the possibility of FDA
approval of a label change is sufficient to avoid conflict in
these cases, it warns, as a “logical conclusion” so too would
be the possibility that the FDA might rewrite its regula
tions or that Congress might amend the Hatch-Waxman
Amendments. Ante, at 14. The logic of this conclusion
escapes me. Conflict analysis necessarily turns on exist
ing law. It thus would be ridiculous to conclude that
federal and state law do not conflict on the ground that the
defendant could have asked a federal agency or Congress
to change the law. Here, by contrast, the Manufacturers’
compliance with their state-law duty to warn did not re
quire them to ask for a change in federal law, as the
majority itself recognizes. See ante, at 13 (“[F]ederal law
would permit the Manufacturers to comply with the state
labeling requirements if, and only if, the FDA and the
brand-name manufacturer changed the brand-name label
to do so”). The FDA already afforded them a mechanism
for attempting to comply with their state-law duties.
Indeed, the majority assumes that FDA regulations re
quired the Manufacturers to request a label change when
they had “reasonable evidence of an association of a seri
ous hazard with a drug.” 21 CFR §201.57(e).
   Second, the majority suggests that any other approach
would render conflict pre-emption “illusory” and “meaning
less.” Ante, at 14. It expresses concern that, without a
robust view of what constitutes conflict, the Supremacy
Clause would not have “any force” except in cases of ex
press pre-emption. 

the majority’s
purported concern is driven by its reductio ad absurdum,
see ante, at 14, n. 6, that concern is itself illusory, for the
reasons just stated. To the extent the majority is con
cerned that our traditionally narrow view of what consti
16                     PLIVA, INC. v. MENSING

                       SOTOMAYOR, J., dissenting

tutes impossibility somehow renders conflict pre-emption
as a whole meaningless, that concern simply makes no
sense: We have repeatedly recognized that conflict pre
emption may be found, even absent impossibility, where
state law “stands as an obstacle to the accomplishment
and execution of the full purposes and objectives of
Congress.” 

(internal quotation
marks omitted); see, e.g., Geier v. American Honda Motor
Co., 

, 886 (2000); Barnett Bank of Marion
Cty., N. A. v. Nelson, 

, 31 (1996); Hines v.
Davidowitz, 

, 67 (1941). The majority’s ex
pansive view of impossibility is thus unnecessary to pre
vent conflict pre-emption from losing all meaning.13
    Third, a plurality of the Court adopts the novel theory
that the Framers intended for the Supremacy Clause to
operate as a so-called non obstante provision. See ante, at
15–17 (citing Nelson, Preemption, 

. Rev. 225
(2000)). According to the plurality, non obstante provi
sions in statutes “instruc[t] courts not to apply the general
presumption against implied repeals.” Ante, at 15 (inter
nal quotation marks omitted); see also ante, at 16 (stating
that when a statute contains a non obstante provision,
“ ‘courts will be less inclined against recognizing repug
nancy in applying such statutes’ ” (quoting J. Sutherland,
Statutes and Statutory Construction §147, p. 199 (1891)).
From this understanding of the Supremacy Clause, the
plurality extrapolates the principle that “courts should not
strain to find ways to reconcile federal law with seemingly
——————
  13 JUSTICE THOMAS, the author of today’s opinion, has previously ex
pressed the view that obstacle pre-emption is inconsistent with the
Constitution. See Williamson v. Mazda Motor of America, Inc., 562
U. S. ___, ___ (2011) (opinion concurring in judgment) (slip op., at 2–5);
Wyeth v. Levine, 

, 604 (2009) (opinion concurring in
judgment). That position, however, has not been accepted by this
Court, and it thus should not justify the majority’s novel expansion of
impossibility pre-emption.
                    Cite as: 564 U. S. ____ (2011)                  17

                      SOTOMAYOR, J., dissenting

conflicting state law.” Ante, at 15.
   This principle would have been news to the Congress
that enacted the Hatch-Waxman Amendments in 1984:
Our precedents hold just the opposite. For more than half
a century, we have directed courts to presume that con
gressional action does not supersede “the historic police
powers of the States . . . unless that was the clear and
manifest purpose of Congress.” Rice v. Santa Fe Elevator
Corp., 

, 230 (1947); see also 

–112 (KENNEDY, J., concurring in part and concur
ring in judgment). We apply this presumption against
pre-emption both where Congress has spoken to the pre
emption question and where it has not. See 

, n. 3. In the context of express pre-emption,
we read federal statutes whenever possible not to pre
empt state law. See Altria Group, Inc. v. Good, 

, 77 (2008) (“[W]hen the text of a pre-emption clause
is susceptible of more than one plausible reading, courts
ordinarily ‘accept the reading that disfavors pre-emption’ ”
(quoting Bates v. Dow Agrosciences LLC, 

,
449 (2005))); see also Cipollone v. Liggett Group, Inc., 

, 518 (1992). And, when the claim is that federal
law impliedly pre-empts state law, we require a “strong”
showing of a conflict “to overcome the presumption that
state and local regulation . . . can constitutionally coexist
with federal regulation.” Hillsborough County v. Auto
mated Medical Laboratories, Inc., 

, 716
(1985).
   The plurality’s new theory of the Supremacy Clause is a
direct assault on these precedents.14 Whereas we have
——————
  14 The author of the law review article proposing this theory of the

Supremacy Clause acknowledges as much. See Nelson, Preemption, 

. Rev. 225, 304 (2000) (“The non obstante provision rejects an
artificial presumption that Congress did not intend to contradict any
state laws and that federal statutes must therefore be harmonized with
state law”). The plurality, on the other hand, carefully avoids discuss
18                   PLIVA, INC. v. MENSING

                      SOTOMAYOR, J., dissenting

long presumed that federal law does not pre-empt, or
repeal, state law, the plurality today reads the Supremacy
Clause to operate as a provision instructing courts “not to
apply the general presumption against implied repeals.”
Ante, at 15 (internal quotation marks omitted; emphasis
added). And whereas we have long required evidence of a
“clear and manifest” purpose to pre-empt, 

, the plurality now instructs courts to “look no fur
ther than the ordinary meaning of federal law” before
concluding that Congress must have intended to cast aside
state law, ante, at 16 (internal quotation marks and al
teration omitted).
   That the plurality finds it necessary to resort to this
novel theory of the Supremacy Clause—a theory advo
cated by no party or amici in these cases—is telling.
Proper application of the longstanding presumption
against pre-emption compels the conclusion that federal
law does not render compliance with state law impossible
merely because it requires an actor to seek federal agency
approval. When federal law provides actors with a mech
anism for attempting to comply with their state-law
duties, “respect for the States as ‘independent sovereigns
in our federal system’ ” should require those actors to
attempt to comply with state law before being heard to
complain that compliance with both laws was impossible.

–566, n. 3 (quoting 

).
                             III
  Today’s decision leads to so many absurd consequences
that I cannot fathom that Congress would have intended
to pre-empt state law in these cases.
  First, the majority’s pre-emption analysis strips generic

—————— 

ing the ramifications of its new theory for the longstanding presump

tion against pre-emption. 

                 Cite as: 564 U. S. ____ (2011)           19

                   SOTOMAYOR, J., dissenting

drug consumers of compensation when they are injured by
inadequate warnings. “If Congress had intended to de
prive injured parties of [this] long available form of com
pensation, it surely would have expressed that intent more
clearly.” 

. Given the longstanding
existence of product liability actions, including for failure
to warn, “[i]t is difficult to believe that Congress would,
without comment, remove all means of judicial recourse
for those injured by illegal conduct.” 

; see also Bruesewitz v. Wyeth LLC, 562 U. S. ___,
___ (2011) (slip op., at 16) (noting our previously expressed
“doubt that Congress would quietly preempt product
liability claims without providing a federal substitute”).
In concluding that Congress silently immunized generic
manufacturers from all failure-to-warn claims, the major
ity disregards our previous hesitance to infer congres
sional intent to effect such a sweeping change in tradi
tional state-law remedies.
   As the majority itself admits, a drug consumer’s right
to compensation for inadequate warnings now turns on
the happenstance of whether her pharmacist filled her pre
scription with a brand-name drug or a generic. If a con
sumer takes a brand-name drug, she can sue the manufac
turer for inadequate warnings under our opinion in Wyeth.
If, however, she takes a generic drug, as occurs 75 percent
of the time, she now has no right to sue. The majority
offers no reason to think—apart from its new articulation
of the impossibility standard—that Congress would have
intended such an arbitrary distinction. In some States,
pharmacists must dispense generic drugs absent instruc
tion to the contrary from a consumer’s physician. Even
when consumers can request brand-name drugs, the price
of the brand-name drug or the consumers’ insurance plans
may make it impossible to do so. As a result, in many
cases, consumers will have no ability to preserve their
state-law right to recover for injuries caused by inade
20                    PLIVA, INC. v. MENSING

                       SOTOMAYOR, J., dissenting

quate warnings.
   Second, the majority’s decision creates a gap in the
parallel federal-state regulatory scheme in a way that
could have troubling consequences for drug safety. As we
explained in Wyeth, “[s]tate tort suits uncover unknown
drug hazards and provide incentives for drug manufactur
ers to disclose safety risks 

.
Thus, we recognized, “state law offers an additional, and
important, layer of consumer protection that complements
FDA regulation.” 

the
traditional state-law incentives for generic manufacturers
to monitor and disclose safety risks. When a generic drug
has a brand-name equivalent on the market, the brand
name manufacturer will remain incentivized to uncover
safety risks. But brand-name manufacturers often leave
the market once generic versions are available, 

–5, meaning that there will be no manufacturer sub
ject to failure-to-warn liability. As to those generic drugs,
there will be no “additional . . . layer of consumer protec
tion.” 

.
   Finally, today’s decision undoes the core principle of
the Hatch-Waxman Amendments that generic and brand
name drugs are the “same” in nearly all respects.15 See
Brief for Rep. Henry A. Waxman as Amicus Curiae 9.
The majority pins the expansion of the generic drug market
on “the special, and different, regulation of generic drugs,”
which allows generic manufacturers to produce their
drugs more cheaply. Ante, at 19. This tells only half the
story. The expansion of the market for generic drugs has
also flowed from the increased acceptance of, and trust in,
——————
  15 According to the GPhA, both the FDA and the generic drug indus

try “spend millions of dollars each year . . . seeking to reassure consum
ers that affordable generic drugs really are—as federal law compels
them to be—the same as their pricier brand-name counterparts.” Brief
for GPhA as Amicus Curiae on Pet. for Cert. in Nos. 09–993, 09–1039,
pp. 2–3.
                 Cite as: 564 U. S. ____ (2011)          21

                  SOTOMAYOR, J., dissenting

generic drugs by consumers, physicians, and state legisla
tors alike.
  Today’s decision introduces a critical distinction be
tween brand-name and generic drugs. Consumers of
brand-name drugs can sue manufacturers for inadequate
warnings; consumers of generic drugs cannot. These
divergent liability rules threaten to reduce consumer
demand for generics, at least among consumers who can
afford brand-name drugs. They may pose “an ethical
dilemma” for prescribing physicians. Brief for American
Medical Association et al. as Amici Curiae 29. And they
may well cause the States to rethink their longstanding
efforts to promote generic use through generic substitution
laws. See Brief for National Conference of State Legisla
tors as Amicus Curiae 15 (state generic substitution laws
“have proceeded on the premise that . . . generic drugs are
not, from citizens’ perspective, materially different from
brand ones, except for the lower price”). These conse
quences are directly at odds with the Hatch-Waxman
Amendments’ goal of increasing consumption of generic
drugs.
  Nothing in the Court’s opinion convinces me that, in
enacting the requirement that generic labels match their
corresponding brand-name labels, Congress intended
these absurd results. The Court certainly has not shown
that such was the “clear and manifest purpose of Con
gress.” 

(internal quotation marks
omitted; emphasis added). To the contrary, because fed
eral law affords generic manufacturers a mechanism for
attempting to comply with their state-law duties to warn,
I would hold that federal law does not categorically
pre-empt state-law failure-to-warn claims against generic
manufacturers. Especially in light of the presumption
against pre-emption, the burden should fall on generic
manufacturers to show that compliance was impossible on
the particular facts of their case. By holding that the
22                 PLIVA, INC. v. MENSING

                   SOTOMAYOR, J., dissenting

“possibility of possibility” is insufficient to “defea[t]” pre
emption in these cases, ante, at 18, n. 8, the Court contorts
our pre-emption doctrine and exempts defendants from
their burden to establish impossibility. With respect,
I dissent.