(Slip Opinion)              OCTOBER TERM, 2011                                       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

   MAYO COLLABORATIVE SERVICES, DBA MAYO 

  MEDICAL LABORATORIES, ET AL. v. PROMETHEUS 

             LABORATORIES, INC. 


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

   No. 10–1150. Argued December 7, 2011—Decided March 20, 2012
Although “laws of nature, natural phenomena, and abstract ideas” are
  not patentable subject matter under §101 of the Patent Act, Diamond
  v. Diehr, 

, 185, “an application of a law of nature . . . to
  a known structure or process may [deserve] patent protection,” 

But to transform an unpatentable law of nature into a patent-
  eligible application of such a law, a patent must do more than simply
  state the law of nature while adding the words “apply it.” See, e.g.,
  Gottschalk v. Benson, 

, 71–72. It must limit its reach to a
  particular, inventive application of the law.
     Respondent, Prometheus Laboratories, Inc. (Prometheus), is the
  sole and exclusive licensee of the two patents at issue, which concern
  the use of thiopurine drugs to treat autoimmune diseases. When in-
  gested, the body metabolizes the drugs, producing metabolites in the
  bloodstream. Because patients metabolize these drugs differently,
  doctors have found it difficult to determine whether a particular pa-
  tient’s dose is too high, risking harmful side effects, or too low, and so
  likely ineffective. The patent claims here set forth processes embody-
  ing researchers’ findings that identify correlations between metabo-
  lite levels and likely harm or ineffectiveness with precision. Each
  claim recites (1) an “administering” step—instructing a doctor to ad-
  minister the drug to his patient—(2) a “determining” step—telling
  the doctor to measure the resulting metabolite levels in the patient’s
  blood—and (3) a “wherein” step—describing the metabolite concen-
  trations above which there is a likelihood of harmful side-effects and
  below which it is likely that the drug dosage is ineffective, and in-
  forming the doctor that metabolite concentrations above or below
2        MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

                    LABORATORIES, INC.

                          Syllabus


    these thresholds “indicate a need” to decrease or increase (respective-
    ly) the drug dosage.
      Petitioners Mayo Collaborative Services and Mayo Clinic Rochester
    (Mayo) bought and used diagnostic tests based on Prometheus’ pa-
    tents. But in 2004 Mayo announced that it intended to sell and mar-
    ket its own, somewhat different, diagnostic test. Prometheus sued
    Mayo contending that Mayo’s test infringed its patents. The District
    Court found that the test infringed the patents but granted summary
    judgment to Mayo, reasoning that the processes claimed by the pa-
    tents effectively claim natural laws or natural phenomena—namely,
    the correlations between thiopurine metabolite levels and the toxicity
    and efficacy of thiopurine drugs—and therefore are not patentable.
    The Federal Circuit reversed, finding the processes to be patent eligi-
    ble under the Circuit’s “machine or transformation test.” On remand
    from this Court for reconsideration in light of Bilski v. Kappos, 561
    U. S. ___, which clarified that the “machine or transformation test” is
    not a definitive test of patent eligibility, id., at ___–___, the Federal
    Circuit reaffirmed its earlier conclusion.
Held: Prometheus’ process is not patent eligible. Pp. 8–24.
    (a) Because the laws of nature recited by Prometheus’ patent
 claims—the relationships between concentrations of certain metabo-
 lites in the blood and the likelihood that a thiopurine drug dosage
 will prove ineffective or cause harm—are not themselves patentable,
 the claimed processes are not patentable unless they have additional
 features that provide practical assurance that the processes are genu-
 ine applications of those laws rather than drafting efforts designed to
 monopolize the correlations. The three additional steps in the
 claimed processes here are not themselves natural laws but neither
 are they sufficient to transform the nature of the claims. The “ad-
 ministering” step simply identifies a group of people who will be in-
 terested in the correlations, namely, doctors who used thiopurine
 drugs to treat patients suffering from autoimmune disorders. Doc-
 tors had been using these drugs for this purpose long before these pa-
 tents existed. And a “prohibition against patenting abstract ideas
 ‘cannot be circumvented by attempting to limit the use of the formula
 to a particular technological environment.’ ” 

, at ___.
 The “wherein” clauses simply tell a doctor about the relevant natural
 laws, adding, at most, a suggestion that they should consider the test
 results when making their treatment decisions. The “determining”
 step tells a doctor to measure patients’ metabolite levels, through
 whatever process the doctor wishes to use. Because methods for
 making such determinations were well known in the art, this step
 simply tells doctors to engage in well-understood, routine, conven-
 tional activity previously engaged in by scientists in the field. Such
                   Cite as: 566 U. S. ____ (2012)                      3

                              Syllabus

activity is normally not sufficient to transform an unpatentable law
of nature into a patent-eligible application of such a law. Parker v.
Flook, 

, 590. Finally, considering the three steps as an
ordered combination adds nothing to the laws of nature that is not
already present when the steps are considered separately. Pp. 8–11.
   (b) A more detailed consideration of the controlling precedents rein-
forces this conclusion. Pp. 11–19.
     (1) Diehr and Flook, the cases most directly on point, both ad-
dressed processes using mathematical formulas that, like laws of na-
ture, are not themselves patentable. In Diehr, the overall process
was patent eligible because of the way the additional steps of the pro-
cess integrated the equation into the process as a 

. These additional steps transformed the process into an in-
ventive application of the formula. But in Flook, the additional steps
of the process did not limit the claim to a particular application, and
the particular chemical processes at issue were all “well known,” to
the point where, putting the formula to the side, there was no “in-
ventive concept” in the claimed application of the 

. Here, the claim presents a case for patentability that is
weaker than Diehr’s patent-eligible claim and no stronger than
Flook’s unpatentable one. The three steps add nothing specific to the
laws of nature other than what is well-understood, routine, conven-
tional activity, previously engaged in by those in the field. Pp. 11–13.
     (2) Further support for the view that simply appending conven-
tional steps, specified at a high level of generality, to laws of nature,
natural phenomena, and abstract ideas cannot make those laws,
phenomena, and ideas patentable is provided in O’Reilly v. Morse, 

, 114–115; Neilson v. Harford, Webster’s Patent Cases 295,
371; 

, at ___–___; and 

, 65, 67.
Pp. 14–16.
     (3) This Court has repeatedly emphasized a concern that patent
law not inhibit future discovery by improperly tying up the use of
laws of nature and the like. See, e.g., 

, 68.
Rewarding with patents those who discover laws of nature might en-
courage their discovery. But because those laws and principles are
“the basic tools of scientific and technological work,” 

there
is a danger that granting patents that tie up their use will inhibit fu-
ture innovation, a danger that becomes acute when a patented pro-
cess is no more than a general instruction to “apply the natural law,”
or otherwise forecloses more future invention than the underlying
discovery could reasonably justify. The patent claims at issue impli-
cate this concern. In telling a doctor to measure metabolite levels
and to consider the resulting measurements in light of the correla-
tions they describe, they tie up his subsequent treatment decision re-
4       MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

                   LABORATORIES, INC.

                         Syllabus


    gardless of whether he changes his dosage in the light of the infer-
    ence he draws using the correlations. And they threaten to inhibit
    the development of more refined treatment recommendations that
    combine Prometheus’ correlations with later discoveries. This rein-
    forces the conclusion that the processes at issue are not patent eligi-
    ble, while eliminating any temptation to depart from case law prece-
    dent. Pp. 16–19.
       (c) Additional arguments supporting Prometheus’ position—that
    the process is patent eligible because it passes the “machine or trans-
    formation test”; that, because the particular laws of nature that the
    claims embody are narrow and specific, the patents should be upheld;
    that the Court should not invalidate these patents under §101 be-
    cause the Patent Act’s other validity requirements will screen out
    overly broad patents; and that a principle of law denying patent cov-
    erage here will discourage investment in discoveries of new diagnos-
    tic laws of nature—do not lead to a different conclusion. Pp. 19–24.

, reversed.

    BREYER, J., delivered the opinion for a unanimous Court.
                        Cite as: 566 U. S. ____ (2012)                              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
                                   _________________

                                   No. 10–1150
                                   _________________


   MAYO COLLABORATIVE SERVICES, DBA MAYO 

   MEDICAL LABORATORIES, ET AL., PETITION-

    ERS v. PROMETHEUS LABORATORIES, INC.

 ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF

           APPEALS FOR THE FEDERAL CIRCUIT

                                [March 20, 2012]


 JUSTICE BREYER delivered the opinion of the Court.
 Section 101 of the Patent Act defines patentable subject
matter. It says:
      “Whoever invents or discovers any new and useful
    process, machine, manufacture, or composition of
    matter, or any new and useful improvement thereof,
    may obtain a patent therefor, subject to the conditions
    and requirements of this title.” 

. §101.
The Court has long held that this provision contains an
important implicit exception. “[L]aws of nature, natural
phenomena, and abstract ideas” are not patentable. Dia-
mond v. Diehr, 

, 185 (1981); see also Bilski v.
Kappos, 561 U. S. ___, ___ (2010) (slip op., at 5); Diamond
v. Chakrabarty, 

, 309 (1980); Le Roy v. Tat-
ham, 

, 175 (1853); O’Reilly v. Morse, 

, 112–120 (1854); cf. Neilson v. Harford, Webster’s
Patent Cases 295, 371 (1841) (English case discussing
same). Thus, the Court has written that “a new mineral
discovered in the earth or a new plant found in the wild is
not patentable subject matter. Likewise, Einstein could
2    MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

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                 Opinion of the Court 


not patent his celebrated law that E=mc2; nor could New­
ton have patented the law of gravity. Such discoveries are
‘manifestations of . . . nature, free to all men and reserved
exclusively to none.’ ” 

(quoting
Funk Brothers Seed Co. v. Kalo Inoculant Co., 

, 130 (1948)).
  “Phenomena of nature, though just discovered, mental
processes, and abstract intellectual concepts are not pa­
tentable, as they are the basic tools of scientific and tech­
nological work.” Gottschalk v. Benson, 

, 67
(1972). And monopolization of those tools through the
grant of a patent might tend to impede innovation more
than it would tend to promote it.
  The Court has recognized, however, that too broad an
interpretation of this exclusionary principle could eviscer­
ate patent law. For all inventions at some level embody,
use, reflect, rest upon, or apply laws of nature, natural
phenomena, or abstract ideas. Thus, in Diehr the Court
pointed out that “ ‘a process is not unpatentable simply
because it contains a law of nature or a mathematical
algorithm.’ 

(quoting Parker v. Flook,

, 590 (1978)). It added that “an application
of a law of nature or mathematical formula to a known
structure or process may well be deserving of patent pro­
tection.” 

. And it emphasized Justice
Stone’s similar observation in Mackay Radio & Telegraph
Co. v. Radio Corp. of America, 

(1939):
      “ ‘While a scientific truth, or the mathematical ex­
    pression of it, is not a patentable invention, a novel
    and useful structure created with the aid of
    knowledge of scientific truth may be.’ 

(quoting Mackay 

).
See also Funk 

(“If there is to be
invention from [a discovery of a law of nature], it must
come from the application of the law of nature to a new
                  Cite as: 566 U. S. ____ (2012)             3

                      Opinion of the Court

and useful end”).
   Still, as the Court has also made clear, to transform an
unpatentable law of nature into a patent-eligible applica-
tion of such a law, one must do more than simply state the
law of nature while adding the words “apply it.” See, e.g.,

–72.
   The case before us lies at the intersection of these basic
principles. It concerns patent claims covering processes
that help doctors who use thiopurine drugs to treat pa­
tients with autoimmune diseases determine whether a
given dosage level is too low or too high. The claims pur­
port to apply natural laws describing the relationships
between the concentration in the blood of certain thiopu­
rine metabolites and the likelihood that the drug dosage
will be ineffective or induce harmful side-effects. We must
determine whether the claimed processes have trans­
formed these unpatentable natural laws into patent­
eligible applications of those laws. We conclude that they
have not done so and that therefore the processes are not
patentable.
   Our conclusion rests upon an examination of the partic­
ular claims before us in light of the Court’s precedents.
Those cases warn us against interpreting patent statutes
in ways that make patent eligibility “depend simply on the
draftsman’s art” without reference to the “principles un­
derlying the prohibition against patents for [natural
laws].” 

. They warn us against up­
holding patents that claim processes that too broadly
preempt the use of a natural law. 

–
120; 

–72. And they insist that a
process that focuses upon the use of a natural law also
contain other elements or a combination of elements,
sometimes referred to as an “inventive concept,” sufficient
to ensure that the patent in practice amounts to signifi­
cantly more than a patent upon the natural law itself.

; see also 

, at ___ (slip op.,
4     MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

                 LABORATORIES, INC.

                  Opinion of the Court 


at 14) (“[T]he prohibition against patenting abstract ideas
‘cannot be circumvented by attempting to limit the use of
the formula to a particular technological environment’ or
adding ‘insignificant postsolution activity’ ” (quoting 

–192)).
   We find that the process claims at issue here do not
satisfy these conditions. In particular, the steps in the
claimed processes (apart from the natural laws them­
selves) involve well-understood, routine, conventional
activity previously engaged in by researchers in the field.
At the same time, upholding the patents would risk dis­
proportionately tying up the use of the underlying nat-
ural laws, inhibiting their use in the making of further
discoveries.
                                I

                               A

  The patents before us concern the use of thiopurine
drugs in the treatment of autoimmune diseases, such as
Crohn’s disease and ulcerative colitis. When a patient
ingests a thiopurine compound, his body metabolizes the
drug, causing metabolites to form in his bloodstream.
Because the way in which people metabolize thiopurine
compounds varies, the same dose of a thiopurine drug
affects different people differently, and it has been difficult
for doctors to determine whether for a particular patient a
given dose is too high, risking harmful side effects, or too
low, and so likely ineffective.
  At the time the discoveries embodied in the patents
were made, scientists already understood that the levels
in a patient’s blood of certain metabolites, including, in
particular, 6-thioguanine and its nucleotides (6–TG) and
6-methyl-mercaptopurine (6–MMP), were correlated with
the likelihood that a particular dosage of a thiopurine
drug could cause harm or prove ineffective. See U. S.
Patent No. 6,355,623, col. 8, ll. 37–40, 

. (“Previ­
                 Cite as: 566 U. S. ____ (2012)            5

                     Opinion of the Court

ous studies suggested that measurement of 6–MP metabo­
lite levels can be used to predict clinical efficacy and tol-
erance to azathioprine or 6–MP” (citing Cuffari, Théorêt,
Latour, & Seidman, 6-Mercaptopurine Metabolism in
Crohn’s Disease: Correlation with Efficacy and Toxicity,
39 Gut 401 (1996))). But those in the field did not know
the precise correlations between metabolite levels and
likely harm or ineffectiveness. The patent claims at issue
here set forth processes embodying researchers’ findings
that identified these correlations with some precision.
   More specifically, the patents—U. S. Patent No.
6,355,623 (’623 patent) and U. S. Patent No. 6,680,302
(’302 patent)—embody findings that concentrations in a
patient’s blood of 6–TG or of 6–MMP metabolite beyond a
certain level (400 and 7000 picomoles per 8x108 red blood
cells, respectively) indicate that the dosage is likely too
high for the patient, while concentrations in the blood of
6–TG metabolite lower than a certain level (about 230
picomoles per 8x108 red blood cells) indicate that the
dosage is likely too low to be effective.
   The patent claims seek to embody this research in a set
of processes. Like the Federal Circuit we take as typical
claim 1 of the ’623 Patent, which describes one of the
claimed processes as follows:
    “A method of optimizing therapeutic efficacy for
    treatment of an immune-mediated gastrointestinal
    disorder, comprising:
    “(a) administering a drug providing 6-thioguanine to
    a subject having said immune-mediated gastrointesti­
    nal disorder; and
    “(b) determining the level of 6-thioguanine in said
    subject having said immune-mediated gastrointesti­
    nal disorder,
    “wherein the level of 6-thioguanine less than about
    230 pmol per 8x108 red blood cells indicates a need to
6    MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

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                 Opinion of the Court 


    increase the amount of said drug subsequently admin­
    istered to said subject and
    “wherein the level of 6-thioguanine greater than about
    400 pmol per 8x108 red blood cells indicates a need to
    decrease the amount of said drug subsequently ad­
    ministered to said subject.” ’623 patent, col. 20, ll. 10–
    20, 

.
For present purposes we may assume that the other
claims in the patents do not differ significantly from
claim 1.
                              B
   Respondent, Prometheus Laboratories, Inc. (Prome­
theus), is the sole and exclusive licensee of the ’623 and
’302 patents. It sells diagnostic tests that embody the
processes the patents describe. For some time petitioners,
Mayo Clinic Rochester and Mayo Collaborative Services
(collectively Mayo), bought and used those tests. But in
2004 Mayo announced that it intended to begin using and
selling its own test—a test using somewhat higher metab­
olite levels to determine toxicity (450 pmol per 8x108 for
6–TG and 5700 pmol per 8x108 for 6–MMP). Prometheus
then brought this action claiming patent infringement.
   The District Court found that Mayo’s test infringed
claim 7 of the ’623 patent. App. to Pet. for Cert. 110a–
115a. In interpreting the claim, the court accepted Prome­
theus’ view that the toxicity-risk level numbers in Mayo’s
test and the claim were too similar to render the tests
significantly different. The number Mayo used (450) was
too close to the number the claim used (400) to matter
given appropriate margins of error. 

The
District Court also accepted Prometheus’ view that a
doctor using Mayo’s test could violate the patent even if he
did not actually alter his treatment decision in the light of
the test. In doing so, the court construed the claim’s lan­
guage, “indicates a need to decrease” (or “to increase”), as
                 Cite as: 566 U. S. ____ (2012)            7

                     Opinion of the Court

not limited to instances in which the doctor actually de­
creases (or increases) the dosage level where the test
results suggest that such an adjustment is advisable. 

see also Brief for Respondent i (describing
claimed processes as methods “for improving . . . treat­
ment . . . by using individualized metabolite measure­
ments to inform the calibration of . . . dosages of . . .
thiopurines” (emphasis added)).
   Nonetheless the District Court ultimately granted
summary judgment in Mayo’s favor. The court reasoned
that the patents effectively claim natural laws or natural
phenomena—namely the correlations between thiopurine
metabolite levels and the toxicity and efficacy of thiopu­
rine drug dosages—and so are not patentable. App. to Pet.
for Cert. 50a–83a.
   On appeal, the Federal Circuit reversed. It pointed out
that in addition to these natural correlations, the claimed
processes specify the steps of (1) “administering a [thiopu­
rine] drug” to a patient and (2) “determining the [resulting
metabolite] level.” These steps, it explained, involve the
transformation of the human body or of blood taken from
the body. Thus, the patents satisfied the Circuit’s “ma­
chine or transformation test,” which the court thought
sufficient to “confine the patent monopoly within rather
definite bounds,” thereby bringing the claims into compli­
ance with §101. 

, 1345, 1346–1347 (2009)
(internal quotation marks omitted).
   Mayo filed a petition for certiorari. We granted the
petition, vacated the judgment, and remanded the case for
reconsideration in light of Bilski, 561 U. S. ___, which
clarified that the “machine or transformation test” is not a
definitive test of patent eligibility, but only an important
and useful clue. Id., at ___–___ (slip op., at 7–8). On
remand the Federal Circuit reaffirmed its earlier conclu­
sion. It thought that the “machine-or-transformation
test,” understood merely as an important and useful clue,
8    MAYO COLLABORATIVE SERVICES v. PROMETHEUS 

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                 Opinion of the Court 


nonetheless led to the “clear and compelling conclusion . . .
that the . . . claims . . . do not encompass laws of nature or
preempt natural correlations.” 

, 1355
(2010). Mayo again filed a petition for certiorari, which we
granted.
                             II
   Prometheus’ patents set forth laws of nature—namely,
relationships between concentrations of certain metabo­
lites in the blood and the likelihood that a dosage of a
thiopurine drug will prove ineffective or cause harm.
Claim 1, for example, states that if the levels of 6–TG in
the blood (of a patient who has taken a dose of a thiopu­
rine drug) exceed about 400 pmol per 8x108 red blood cells,
then the administered dose is likely to produce toxic side
effects. While it takes a human action (the administration
of a thiopurine drug) to trigger a manifestation of this
relation in a particular person, the relation itself exists in
principle apart from any human action. The relation is a
consequence of the ways in which thiopurine compounds
are metabolized by the body—entirely natural processes.
And so a patent that simply describes that relation sets
forth a natural law.
   The question before us is whether the claims do signifi­
cantly more than simply describe these natural relations.
To put the matter more precisely, do the patent claims add
enough to their statements of the correlations to allow the
processes they describe to qualify as patent-eligible pro­
cesses that apply natural laws? We believe that the an­
swer to this question is no.
                            A
  If a law of nature is not patentable, then neither is a
process reciting a law of nature, unless that process has
additional features that provide practical assurance that
the process is more than a drafting effort designed to
                 Cite as: 566 U. S. ____ (2012)           9

                     Opinion of the Court

monopolize the law of nature itself. A patent, for example,
could not simply recite a law of nature and then add the
instruction “apply the law.” Einstein, we assume, could
not have patented his famous law by claiming a process
consisting of simply telling linear accelerator operators to
refer to the law to determine how much energy an amount
of mass has produced (or vice versa). Nor could Archime­
des have secured a patent for his famous principle of
flotation by claiming a process consisting of simply telling
boat builders to refer to that principle in order to deter­
mine whether an object will float.
   What else is there in the claims before us? The process
that each claim recites tells doctors interested in the
subject about the correlations that the researchers discov­
ered. In doing so, it recites an “administering” step, a
“determining” step, and a “wherein” step. These addition­
al steps are not themselves natural laws but neither are
they sufficient to transform the nature of the claim.
   First, the “administering” step simply refers to the
relevant audience, namely doctors who treat patients with
certain diseases with thiopurine drugs. That audience is
a pre-existing audience; doctors used thiopurine drugs to
treat patients suffering from autoimmune disorders long
before anyone asserted these claims. In any event, the
“prohibition against patenting abstract ideas ‘cannot be
circumvented by attempting to limit the use of the formula
to a particular technological environment.’ ” 

,
at ___ (slip op., at 14) (quoting 

–
192).
   Second, the “wherein” clauses simply tell a doctor about
the relevant natural laws, at most adding a suggestion
that he should take those laws into account when treating
his patient. That is to say, these clauses tell the relevant
audience about the laws while trusting them to use those
laws appropriately where they are relevant to their deci­
sionmaking (rather like Einstein telling linear accelerator
10   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
                LABORATORIES, INC.
                 Opinion of the Court

operators about his basic law and then trusting them to
use it where relevant).
   Third, the “determining” step tells the doctor to deter­
mine the level of the relevant metabolites in the blood,
through whatever process the doctor or the laboratory
wishes to use. As the patents state, methods for determin­
ing metabolite levels were well known in the art. ’623
patent, col. 9, ll. 12–65, 

. Indeed, scientists
routinely measured metabolites as part of their investiga­
tions into the relationships between metabolite levels and
efficacy and toxicity of thiopurine compounds. ’623 patent,
col. 8, ll. 37–40, 

Thus, this step tells doctors
to engage in well-understood, routine, conventional activity
previously engaged in by scientists who work in the field.
Purely “conventional or obvious” “[pre]-solution activity” is
normally not sufficient to transform an unpatentable law
of nature into a patent-eligible application of such a law.

; see also Bilski, 561 U. S., at ___
(slip op., at 14) (“[T]he prohibition against patenting ab­
stract ideas ‘cannot be circumvented by’ . . . adding ‘insig­
nificant post-solution activity’ ” (quoting 

–192)).
   Fourth, to consider the three steps as an ordered combi­
nation adds nothing to the laws of nature that is not al­
ready present when the steps are considered separately.
See 

(“[A] new combination of steps in
a process may be patentable even though all the constitu­
ents of the combination were well known and in common
use before the combination was made”). Anyone who
wants to make use of these laws must first administer a
thiopurine drug and measure the resulting metabolite
concentrations, and so the combination amounts to noth­
ing significantly more than an instruction to doctors to
apply the applicable laws when treating their patients.
   The upshot is that the three steps simply tell doctors to
gather data from which they may draw an inference in
                 Cite as: 566 U. S. ____ (2012)           11

                     Opinion of the Court

light of the correlations. To put the matter more suc­
cinctly, the claims inform a relevant audience about
certain laws of nature; any additional steps consist of well­
understood, routine, conventional activity already engaged
in by the scientific community; and those steps, when
viewed as a whole, add nothing significant beyond the sum
of their parts taken separately. For these reasons we
believe that the steps are not sufficient to transform un­
patentable natural correlations into patentable applica­
tions of those regularities.
                             B
                             1
  A more detailed consideration of the controlling prece­
dents reinforces our conclusion. The cases most directly
on point are Diehr and Flook, two cases in which the Court
reached opposite conclusions about the patent eligibility of
processes that embodied the equivalent of natural laws.
The Diehr process (held patent eligible) set forth a method
for molding raw, uncured rubber into various cured, mold­
ed products. The process used a known mathematical
equation, the Arrhenius equation, to determine when
(depending upon the temperature inside the mold, the
time the rubber had been in the mold, and the thickness of
the rubber) to open the press. It consisted in effect of the
steps of: (1) continuously monitoring the temperature on
the inside of the mold, (2) feeding the resulting numbers
into a computer, which would use the Arrhenius equation
to continuously recalculate the mold-opening time, and (3)
configuring the computer so that at the appropriate mo­
ment it would signal “a device” to open the press. 

–179.
  The Court pointed out that the basic mathematical
equation, like a law of nature, was not patentable. But
it found the overall process patent eligible because of
the way the additional steps of the process integrated the
12   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                 Opinion of the Court

equation into the process as a whole. Those steps included
“installing rubber in a press, closing the mold, constantly
determining the temperature of the mold, constantly re-
calculating the appropriate cure time through the use of
the formula and a digital computer, and automatically
opening the press at the proper time.” 

It
nowhere suggested that all these steps, or at least the
combination of those steps, were in context obvious, al­
ready in use, or purely conventional. And so the patentees
did not “seek to pre-empt the use of [the] equation,” but
sought “only to foreclose from others the use of that equa­
tion in conjunction with all of the other steps in their
claimed process.” 

apparently
added to the formula something that in terms of patent
law’s objectives had significance—they transformed the
process into an inventive application of the formula.
   The process in Flook (held not patentable) provided a
method for adjusting “alarm limits” in the catalytic con­
version of hydrocarbons. Certain operating conditions
(such as temperature, pressure, and flow rates), which are
continuously monitored during the conversion process,
signal inefficiency or danger when they exceed certain
“alarm limits.” The claimed process amounted to an im­
proved system for updating those alarm limits through the
steps of: (1) measuring the current level of the variable,
e.g., the temperature; (2) using an apparently novel math­
ematical algorithm to calculate the current alarm limits;
and (3) adjusting the system to reflect the new alarm-limit

–587.
   The Court, as in Diehr, pointed out that the basic math­
ematical equation, like a law of nature, was not patenta­
ble. But it characterized the claimed process as doing
nothing other than “provid[ing] a[n unpatentable] formula
for computing an updated alarm limit.” 

. Unlike the process in Diehr, it did not “explain how
the variables used in the formula were to be selected, nor
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                      Opinion of the Court

did the [claim] contain any disclosure relating to chemical
processes at work or the means of setting off an alarm or
adjusting the alarm limit.” 

, n. 14; see
also 

. And so the other steps in the
process did not limit the claim to a particular application.
Moreover, “[t]he chemical processes involved in catalytic
conversion of hydrocarbons[,] . . . the practice of monitor­
ing the chemical process variables, the use of alarm limits
to trigger alarms, the notion that alarm limit values must
be recomputed and readjusted, and the use of comput-
ers for ‘automatic monitoring-alarming’ ” were all “well
known,” to the point where, putting the formula to the
side, there was no “inventive concept” in the claimed
application of the formula. 

“[P]ost-solution
activity” that is purely “conventional or obvious,” the
Court wrote, “can[not] transform an unpatentable princi­
ple into a patentable process.” 

590.
  The claim before us presents a case for patentability
that is weaker than the (patent-eligible) claim in Diehr
and no stronger than the (unpatentable) claim in Flook.
Beyond picking out the relevant audience, namely those
who administer doses of thiopurine drugs, the claim sim-
ply tells doctors to: (1) measure (somehow) the current level
of the relevant metabolite, (2) use particular (unpatenta­
ble) laws of nature (which the claim sets forth) to calculate
the current toxicity/inefficacy limits, and (3) reconsider the
drug dosage in light of the law. These instructions add
nothing specific to the laws of nature other than what is
well-understood, routine, conventional activity, previously
engaged in by those in the field. And since they are steps
that must be taken in order to apply the laws in question,
the effect is simply to tell doctors to apply the law some­
how when treating their patients. The process in Diehr
was not so characterized; that in Flook was characterized
in roughly this way.
14    MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                  Opinion of the Court

                             2
  Other cases offer further support for the view that simp­
ly appending conventional steps, specified at a high level
of generality, to laws of nature, natural phenomena, and
abstract ideas cannot make those laws, phenomena, and
ideas patentable. This Court has previously discussed in
detail an English case, Neilson, which involved a patent
claim that posed a legal problem very similar to the prob­
lem now before us. The patent applicant there asserted a
claim
     “for the improved application of air to produce heat in
     fires, forges, and furnaces, where a blowing apparatus
     is required. [The invention] was to be applied as
     follows: The blast or current of air produced by the
     blowing apparatus was to be passed from it into
     an air-vessel or receptacle made sufficiently strong to
     endure the blast; and through or from that vessel or
     receptacle by means of a tube, pipe, or aperture into
     the fire, the receptacle be kept artificially heated to a
     considerable temperature by heat externally applied.”
     

–115.
The English court concluded that the claimed process did
more than simply instruct users to use the principle that
hot air promotes ignition better than cold air, since it
explained how the principle could be implemented in an
inventive way. Baron Parke wrote (for the court):
     “It is very difficult to distinguish [Neilson’s claim]
     from the specification of a patent for a principle, and
     this at first created in the minds of some of the court
     much difficulty; but after full consideration, we think
     that the plaintiff does not merely claim a principle,
     but a machine embodying a principle, and a very val­
     uable one. We think the case must be considered as if
     the principle being well known, the plaintiff had first
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                      Opinion of the Court

    invented a mode of applying it by a mechanical appa­
    ratus to furnaces; and his invention then consists in
    this—by interposing a receptacle for heated air be­
    tween the blowing apparatus and the furnace. In this
    receptacle he directs the air to be heated by the appli­
    cation of heat externally to the receptacle, and thus he
    accomplishes the object of applying the blast, which
    was before of cold air, in a heated state to the fur­
    nace.” Neilson v. Harford, Webster’s Patent Cases, at
    371.
Thus, the claimed process included not only a law of
nature but also several unconventional steps (such as
inserting the receptacle, applying heat to the receptacle
externally, and blowing the air into the furnace) that
confined the claims to a particular, useful application of the
principle.
   In Bilski the Court considered claims covering a process
for hedging risks of price changes by, for example, con­
tracting to purchase commodities from sellers at a fixed
price, reflecting the desire of sellers to hedge against a
drop in prices, while selling commodities to consumers at a
fixed price, reflecting the desire of consumers to hedge
against a price increase. One claim described the process;
another reduced the process to a mathematical formula.
561 U. S., at ___–___ (slip op., at 2–3). The Court held
that the described “concept of hedging” was “an unpatent­
able abstract idea.” Id., at ___ (slip op., at 15). The fact
that some of the claims limited hedging to use in commod­
ities and energy markets and specified that “well-known
random analysis techniques [could be used] to help estab­
lish some of the inputs into the equation” did not under­
mine this conclusion, for “Flook established that limiting
an abstract idea to one field of use or adding token postso­
lution components did not make the concept patentable.”
Id., at ___, ___ (slip op., at 16, 15).
16    MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                  Opinion of the Court

   Finally, in Benson the Court considered the patentabil­
ity of a mathematical process for converting binary-coded
decimal numerals into pure binary numbers on a general
purpose digital computer. The claims “purported to cover
any use of the claimed method in a general-purpose digital
computer of any 

, 65. The Court
recognized that “ ‘a novel and useful structure created with
the aid of knowledge of scientific truth’ ” might be patent­
able. 

(quoting Mackay 

).
But it held that simply implementing a mathematical
principle on a physical machine, namely a computer, was
not a patentable application of that principle. For the
mathematical formula had “no substantial practical appli­
cation except in connection with a digital computer.”

. Hence the claim (like the claims
before us) was overly broad; it did not differ significantly
from a claim that just said “apply the algorithm.”
                               3
   The Court has repeatedly emphasized this last men­
tioned concern, a concern that patent law not inhibit
further discovery by improperly tying up the future use of
laws of nature. Thus, in Morse the Court set aside as
unpatentable Samuel Morse’s general claim for “ ‘the use
of the motive power of the electric or galvanic current . . .
however developed, for making or printing intelligible
characters, letters, or signs, at any distances,’ 

. 	The Court explained:
     “For aught that we now know some future inventor, in
     the onward march of science, may discover a mode of
     writing or printing at a distance by means of the elec­
     tric or galvanic current, without using any part of the
     process or combination set forth in the plaintiff ’s spec­
     ification. His invention may be less complicated—less
     liable to get out of order—less expensive in construc­
     tion, and in its operation. But yet if it is covered by
                 Cite as: 566 U. S. ____ (2012)           17

                     Opinion of the Court

    this patent the inventor could not use it, nor the pub­
    lic have the benefit of it without the permission of this
    patentee.” 

   Similarly, in Benson the Court said that the claims
before it were “so abstract and sweeping as to cover both
known and unknown uses of the [mathematical 

, 68. In Bilski the Court pointed out that
to allow “petitioners to patent risk hedging would pre­
empt use of this approach in all fields.” 561 U. S., at ___
(slip op., at 15). And in Flook the Court expressed concern
that the claimed process was simply “a formula for compu­
ting an updated alarm limit,” which might “cover a broad
range of potential 

.
   These statements reflect the fact that, even though
rewarding with patents those who discover new laws of
nature and the like might well encourage their discovery,
those laws and principles, considered generally, are “the
basic tools of scientific and technological work.” 

. And so there is a danger that the grant of
patents that tie up their use will inhibit future innovation
premised upon them, a danger that becomes acute when a
patented process amounts to no more than an instruction
to “apply the natural law,” or otherwise forecloses more
future invention than the underlying discovery could
reasonably justify. See generally Lemley, Risch, Sichel­
man, & Wagner, Life After Bilski, 63 Stan. L. Rev. 1315
(2011) (hereinafter Lemley) (arguing that §101 reflects
this kind of concern); see also C. Bohannan & H.
Hovenkamp, Creation without Restraint: Promoting Lib­
erty and Rivalry in Innovation 112 (2012) (“One problem
with [process] patents is that the more abstractly their
claims are stated, the more difficult it is to determine
precisely what they cover. They risk being applied to a
wide range of situations that were not anticipated by the
patentee”); W. Landes & R. Posner, The Economic Struc­
18   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                 Opinion of the Court

ture of Intellectual Property Law 305–306 (2003) (The
exclusion from patent law of basic truths reflects “both . . .
the enormous potential for rent seeking that would be
created if property rights could be obtained in them and
. . . the enormous transaction costs that would be imposed
on would-be users [of those truths]”).
    The laws of nature at issue here are narrow laws that
may have limited applications, but the patent claims that
embody them nonetheless implicate this concern. They
tell a treating doctor to measure metabolite levels and to
consider the resulting measurements in light of the statis­
tical relationships they describe. In doing so, they tie up
the doctor’s subsequent treatment decision whether that
treatment does, or does not, change in light of the infer­
ence he has drawn using the correlations. And they
threaten to inhibit the development of more refined treat­
ment recommendations (like that embodied in Mayo’s
test), that combine Prometheus’ correlations with later
discovered features of metabolites, human physiology or
individual patient characteristics. The “determining” step
too is set forth in highly general language covering all
processes that make use of the correlations after measur­
ing metabolites, including later discovered processes that
measure metabolite levels in new ways.
    We need not, and do not, now decide whether were the
steps at issue here less conventional, these features of
the claims would prove sufficient to invalidate them. For
here, as we have said, the steps add nothing of signifi­
cance to the natural laws themselves. Unlike, say, a
typical patent on a new drug or a new way of using an
existing drug, the patent claims do not confine their reach
to particular applications of those laws. The presence here
of the basic underlying concern that these patents tie up
too much future use of laws of nature simply reinforces
our conclusion that the processes described in the patents
are not patent eligible, while eliminating any temptation
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                      Opinion of the Court

to depart from case law precedent.
                             III
   We have considered several further arguments in sup­
port of Prometheus’ position. But they do not lead us to
adopt a different conclusion. First, the Federal Circuit, in
upholding the patent eligibility of the claims before us,
relied on this Court’s determination that “[t]ransformation
and reduction of an article ‘to a different state or thing’ is
the clue to the patentability of a process claim that does
not include particular machines.” 

–71
(emphasis added); see also 

, at ___ (slip op., at
6–7); 

; 

, n. 9;
Cochrane v. Deener, 

, 788 (1877). It reasoned
that the claimed processes are therefore patent eligible,
since they involve transforming the human body by ad­
ministering a thiopurine drug and transforming the blood
by analyzing it to determine metabolite 

–1357.
   The first of these transformations, however, is irrele­
vant. As we have pointed out, the “administering” step
simply helps to pick out the group of individuals who are
likely interested in applying the law of nature. 

. And the second step could be satisfied without trans­
forming the blood, should science develop a totally differ­
ent system for determining metabolite levels that did not
involve such a transformation. 

. Regard­
less, in stating that the “machine-or-transformation” test
is an “important and useful clue” to patentability, we have
neither said nor implied that the test trumps the “law of
nature” exclusion. 

, at ___ (slip op., at 6–7)
(emphasis added). That being so, the test fails here.
   Second, Prometheus argues that, because the particular
laws of nature that its patent claims embody are narrow
and specific, the patents should be upheld. Thus, it en­
courages us to draw distinctions among laws of nature
20   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                 Opinion of the Court

based on whether or not they will interfere significantly
with innovation in other fields now or in the future. Brief
for Respondent 42–46; see also Lemley 1342–1344 (mak­
ing similar argument).
   But the underlying functional concern here is a relative
one: how much future innovation is foreclosed relative to
the contribution of the inventor. 

. A
patent upon a narrow law of nature may not inhibit future
research as seriously as would a patent upon Einstein’s
law of relativity, but the creative value of the discovery is
also considerably smaller. And, as we have previously
pointed out, even a narrow law of nature (such as the
one before us) can inhibit future research. 

–18.
   In any event, our cases have not distinguished among
different laws of nature according to whether or not the
principles they embody are sufficiently narrow. See, e.g.,
Flook, 

(holding narrow mathematical formu­
la unpatentable). And this is understandable. Courts and
judges are not institutionally well suited to making the
kinds of judgments needed to distinguish among differ-
ent laws of nature. And so the cases have endorsed a
bright-line prohibition against patenting laws of nature,
mathematical formulas and the like, which serves as a
somewhat more easily administered proxy for the underlying
“building-block” concern.
   Third, the Government argues that virtually any step
beyond a statement of a law of nature itself should trans­
form an unpatentable law of nature into a potentially
patentable application sufficient to satisfy §101’s de­
mands. Brief for United States as Amicus Curiae. The
Government does not necessarily believe that claims that
(like the claims before us) extend just minimally beyond a
law of nature should receive patents. But in its view,
other statutory provisions—those that insist that a
claimed process be novel, 

. §102, that it not be
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                      Opinion of the Court

“obvious in light of prior art,” §103, and that it be “full[y],
clear[ly], concise[ly], and exact[ly]” described, §112—can
perform this screening function. In particular, it argues
that these claims likely fail for lack of novelty under §102.
   This approach, however, would make the “law of nature”
exception to §101 patentability a dead letter. The ap­
proach is therefore not consistent with prior law. The
relevant cases rest their holdings upon section 101, not
later sections. Bilski, 561 U. S. ___; 

; Flook,
supra; Benson, 

. See also H. R. Rep. No. 1923,
82d Cong., 2d Sess., 6 (1952) (“A person may have ‘invent­
ed’ a machine or a manufacture, which may include any­
thing under the sun that is made by man, but it is not
necessarily patentable under section 101 unless the condi­
tions of the title are fulfilled” (emphasis added)).
   We recognize that, in evaluating the significance of
additional steps, the §101 patent-eligibility inquiry and,
say, the §102 novelty inquiry might sometimes overlap.
But that need not always be so. And to shift the patent­
eligibility inquiry entirely to these later sections risks
creating significantly greater legal uncertainty, while
assuming that those sections can do work that they are
not equipped to do.
   What role would laws of nature, including newly discov­
ered (and “novel”) laws of nature, play in the Govern­
ment’s suggested “novelty” inquiry? Intuitively, one would
suppose that a newly discovered law of nature is novel.
The Government, however, suggests in effect that the
novelty of a component law of nature may be disregarded
when evaluating the novelty of the whole. See Brief for
United States as Amicus Curiae 27. But §§102 and 103
say nothing about treating laws of nature as if they were
part of the prior art when applying those sections. Cf.

(patent claims “must be consid­
ered as a whole”). And studiously ignoring all laws of
nature when evaluating a patent application under §§102
22   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                 Opinion of the Court

and 103 would “make all inventions unpatentable because
all inventions can be reduced to underlying principles of
nature which, once known, make their implementation
obvious.” 

n. 12. See also Eisenberg, Wisdom of
the Ages or Dead-Hand Control? Patentable Subject
Matter for Diagnostic Methods After In re Bilski, 3 Case
W. Res. J. L. Tech. & Internet 1, ___ (forthcoming, 2012)
(manuscript, at 85–86, online at http://www.patentlyo.com/
files/eisenberg.wisdomordeadhand.patentlyo.pdf (as vis­
ited Mar. 16, 2012, and available in Clerk of Court’s
case file)); 2 D. Chisum, Patents §5.03[3] (2005).
   Section 112 requires only a “written description of the
invention . . . in such full, clear, concise, and exact terms
as to enable any person skilled in the art . . . to make and
use the same.” It does not focus on the possibility that a
law of nature (or its equivalent) that meets these condi­
tions will nonetheless create the kind of risk that under­
lies the law of nature exception, namely the risk that a
patent on the law would significantly impede future in-
novation. See Lemley 1329–1332 (outlining differences
between §§101 and 112); 

, at ___ (manu­
script, at 92–96) (similar). Compare Risch, Everything
is Patentable, 

. Rev. 591 (2008) (defending a
minimalist approach to §101) with Lemley (reflecting
Risch’s change of mind).
   These considerations lead us to decline the Govern­
ment’s invitation to substitute §§102, 103, and 112 inquir­
ies for the better established inquiry under §101.
   Fourth, Prometheus, supported by several amici, argues
that a principle of law denying patent coverage here will
interfere significantly with the ability of medical research­
ers to make valuable discoveries, particularly in the area
of diagnostic research. That research, which includes
research leading to the discovery of laws of nature, is
expensive; it “ha[s] made the United States the world
leader in this field”; and it requires protection. Brief for
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                      Opinion of the Court

Respondent 52.
   Other medical experts, however, argue strongly against
a legal rule that would make the present claims patent
eligible, invoking policy considerations that point in the
opposite direction. The American Medical Association, the
American College of Medical Genetics, the American
Hospital Association, the American Society of Human
Genetics, the Association of American Medical Colleges,
the Association for Molecular Pathology, and other medi­
cal organizations tell us that if “claims to exclusive rights
over the body’s natural responses to illness and medical
treatment are permitted to stand, the result will be a vast
thicket of exclusive rights over the use of critical scientific
data that must remain widely available if physicians are
to provide sound medical care.” Brief for American Col­
lege of Medical Genetics et al. as Amici Curiae 7; see also
App. to Brief for Association Internationale pour la Protec­
tion de la Propriété Intellectuelle et al. as Amici Curiae
A6, A16 (methods of medical treatment are not patentable
in most of Western Europe).
   We do not find this kind of difference of opinion surpris­
ing. Patent protection is, after all, a two-edged sword. On
the one hand, the promise of exclusive rights provides
monetary incentives that lead to creation, invention, and
discovery. On the other hand, that very exclusivity can
impede the flow of information that might permit, indeed
spur, invention, by, for example, raising the price of using
the patented ideas once created, requiring potential users
to conduct costly and time-consuming searches of existing
patents and pending patent applications, and requiring
the negotiation of complex licensing arrangements. At the
same time, patent law’s general rules must govern in­
ventive activity in many different fields of human endeav­
or, with the result that the practical effects of rules that
reflect a general effort to balance these considerations
may differ from one field to another. See Bohannan &
24   MAYO COLLABORATIVE SERVICES v. PROMETHEUS
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                 Opinion of the Court

Hovenkamp, Creation without Restraint, at 98–100.
  In consequence, we must hesitate before departing from
established general legal rules lest a new protective rule
that seems to suit the needs of one field produce unfore­
seen results in another. And we must recognize the role of
Congress in crafting more finely tailored rules where
necessary. Cf. 

. §§161–164 (special rules for
plant patents). We need not determine here whether,
from a policy perspective, increased protection for discov­
eries of diagnostic laws of nature is desirable.
                         *    *   *
  For these reasons, we conclude that the patent claims at
issue here effectively claim the underlying laws of nature
themselves. The claims are consequently invalid. And the
Federal Circuit’s judgment is reversed.
                                           It is so ordered.