FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


KEITH ANDREW MITCHELL,                    No. 12-55041
             Petitioner-Appellant,
                                             D.C. No.
                v.                        2:08-cv-00562-
                                            RGK-FFM
ELVIN VALENZUELA, Warden,
            Respondent-Appellee.            OPINION


     Appeal from the United States District Court
        for the Central District of California
     R. Gary Klausner, District Judge, Presiding

              Argued and Submitted
       December 8, 2014—Pasadena, California

                     Filed July 1, 2015

   Before: Harry Pregerson, Kim McLane Wardlaw,
        and Marsha S. Berzon, Circuit Judges.

              Opinion by Judge Berzon
2                  MITCHELL V. VALENZUELA

                           SUMMARY*


                          Habeas Corpus

    Vacating the district court’s judgment dismissing a habeas
corpus petition and remanding, the panel held that a motion
to stay and abey a 28 U.S.C. § 2254 habeas petition to permit
exhaustion of some of the petitioner’s claims in state court is
generally (but not always) dispositive as to the unexhausted
claims, and that a magistrate judge therefore generally cannot
hear and determine such a motion, but rather must submit a
report and recommendation to the district court.

    The panel held that the magistrate judge’s order in this
case was effectively dispositive of the unexhausted claims
and, therefore, beyond his authority.


                            COUNSEL

Sean Kennedy, Federal Public Defender, Michael David
Weinstein (argued), Assistant Federal Public Defender, and
Mark Raymond Drozdowski, Deputy Federal Public
Defender, Federal Public Defender’s Office, Los Angeles,
California for Petitioner-Appellant.

Kamala Harris, Attorney General, Dane Gillette, Chief
Assistant Attorney General, Lance Winters, Senior Assistant
Attorney General, Michael Johnsen, Supervising Deputy
Attorney General, Kim Aarons (argued) and Ana Duarte,

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                 MITCHELL V. VALENZUELA                      3

Deputy Attorneys General, Office of the California Attorney
General, Los Angeles, California for Respondent-Appellee.


                         OPINION

BERZON, Circuit Judge:

    A magistrate judge denied petitioner Keith Andrew
Mitchell’s motion to stay and abey his 28 U.S.C. § 2254
habeas corpus petition while he exhausted some of his claims
in state court. We hold that, in the context of a section 2254
habeas petition, this type of motion is generally (but not
always) dispositive as to the unexhausted claims. When it is
dispositive, a magistrate judge is without authority to “hear
and determine” such a motion, but rather must submit a report
and recommendation to the district court. 28 U.S.C.
§ 636(b)(1)(A)–(B).

                              I.

    Keith Andrew Mitchell was convicted of first degree
murder at a jury trial in California state court. He was
sentenced to fifty years to life in prison. On direct appeal,
Mitchell, represented by counsel, raised several claims
challenging the trial court’s jury instructions. The California
Court of Appeal and California Supreme Court denied relief.

    Proceeding pro se, Mitchell then filed his first federal
habeas petition. The state moved to dismiss the petition for
failure to exhaust some of the claims, and Mitchell
voluntarily dismissed the petition without prejudice so he
could exhaust his state remedies.
4                MITCHELL V. VALENZUELA

    Still within the statute of limitations, 28 U.S.C.
§ 2244(d)(1), and proceeding pro se, Mitchell then filed a
second federal habeas petition, at issue in this case, asserting
five due process claims. Three of the claims corresponded to
the arguments he had presented to the California courts on
direct appeal. The other two claims, both relating to a gang
sentencing enhancement, had been asserted in the first federal
petition. The new petition was referred to a magistrate judge,
authorized by the district court “to consider preliminary
matters and conduct all further hearings as may be
appropriate or necessary,” and thereafter to issue a report and
recommendation to the judge.

    The state once again moved to dismiss the petition,
arguing that the two gang claims were not exhausted. As a
result, the state argued, the petition was “mixed,” and the
only proper resolutions were either to strike the unexhausted
claims or to dismiss the entire petition.

    Mitchell responded by filing a motion to stay the case to
allow him to exhaust the two claims, citing Rhines v. Weber,

(2005). He represented that he had already filed
state habeas petitions regarding the two claims, and that he
had reasonably relied on his appointed attorney in the state
proceedings to raise all of his potential claims on direct
appeal. The state opposed the motion, arguing that there was
no evidence Mitchell actually had filed any state habeas
petition.

   The magistrate judge issued an order addressing both the
motion to dismiss and the motion to stay. Although Mitchell
had not filed an opposition to the motion to dismiss, the
magistrate judge concluded that Mitchell’s motion to stay
“impliedly concede[d] that at least one of his claims is
                 MITCHELL V. VALENZUELA                        5

unexhausted.” The magistrate judge also reviewed the record
and concluded that the two gang claims had not been raised
in the state direct appeals and that Mitchell had offered no
proof that the alleged state habeas petitions had been filed.
As a result, the magistrate judge concluded, the motion to
dismiss was “well taken.”

    As for the motion to stay, the magistrate judge noted that
Rhines requires a showing of good cause for the failure to
exhaust claims in state court. He found that a stay would be
“inappropriate” in this case, as Mitchell had dismissed his
prior petition “specifically to exhaust his state remedies with
respect to the two unexhausted claims” also asserted in the
current petition, yet “took no action to exhaust those claims.”

    The magistrate judge then returned to the motion to
dismiss, noting that, as a mixed petition not eligible for a stay
under Rhines, the petition was “subject to dismissal.” The
magistrate judge granted Mitchell leave to amend his petition
to remove the unexhausted claims and indicated that, if
Mitchell declined to do so, the magistrate judge would “issue
a recommendation that the Petition be dismissed without
prejudice for failure to exhaust.”

   Mitchell did move to remove “all unexhausted claims”
from his petition. The magistrate judge granted Mitchell’s
motion and denied the motion to dismiss as moot.

    Subsequently, the magistrate judge issued a report and
recommendation to the district judge regarding the pared-
down petition. In discussing the case’s procedural history,
the magistrate judge noted that he had previously denied
Mitchell’s stay motion for lack of good cause, had granted
Mitchell’s motion to dismiss his unexhausted claims, and had
6                MITCHELL V. VALENZUELA

denied the state’s motion to dismiss as moot. On the merits
of the remaining three claims, the magistrate judge
recommended that the court deny relief. Mitchell objected,
also on the merits of the three exhausted claims.

    After de novo review, the district court adopted the report
and recommendation and dismissed the petition with
prejudice. The district court did not address the denial of the
stay motion at all. Mitchell timely appealed.

    We granted a certificate of appealability, see 28 U.S.C.
§ 2253(c), as to “whether the magistrate judge exceeded his
authority by issuing, without the parties’ consent, orders
denying appellant’s motion for a stay and abeyance,
dismissing two of appellant’s claims, and denying as moot
appellee’s motion to dismiss.”

                              II.

   The authority of magistrate judges “is a question of law
subject to de novo review.” United States v. Carr, 

, 740 (9th Cir. 1994).

    “The power of federal magistrate judges is limited by
28 U.S.C. § 636.” Estate of Conners by Meredith v.
O’Connor, 

, 658 (9th Cir. 1993) (citing Reynaga
v. Cammisa, 

, 416 (9th Cir. 1992)); see also
Flam v. Flam, — F.3d ––, No. 12-17285, 

at *2 (9th Cir. June 8, 2015). Pursuant to section 636,
magistrate judges may hear and determine nondispositive
matters, but not dispositive matters, in § 2254 proceedings.
Hunt v. Pliler, 

, 1123 (9th Cir. 2004).
Dispositive matters are those listed in section 636(b)(1)(A),
as well as “analogous” matters. See Flam, 

                     MITCHELL V. VALENZUELA                           7

at *2; United States v. Rivera-Guerrero, 

, 1067
(9th Cir. 2004); accord PowerShare, Inc. v. Syntel, Inc., 

, 13 (1st Cir. 2010); Vogel v. U.S. Office Prods. Co.,

, 515 (6th Cir. 2001).1 “To determine whether
a motion is dispositive, we have adopted a functional
approach that looks to the effect of the motion, in order to
determine whether it is properly characterized as dispositive
or non-dispositive of a claim or defense of a party.” Flam,

at *2 (internal quotation marks and
alteration omitted). As to any dispositive matter, the


 1
     28 U.S.C. § 636(b)(1) provides:

          Notwithstanding any provision of law to the contrary–

          (A) a judge may designate a magistrate judge to hear
          and determine any pretrial matter pending before the
          court, except a motion for injunctive relief, for
          judgment on the pleadings, for summary judgment, to
          dismiss or quash an indictment or information made by
          the defendant, to suppress evidence in a criminal case,
          to dismiss or to permit maintenance of a class action, to
          dismiss for failure to state a claim upon which relief
          can be granted, and to involuntarily dismiss an action.
          A judge of the court may reconsider any pretrial matter
          under this subparagraph (A) where it has been shown
          that the magistrate judge’s order is clearly erroneous or
          contrary to law.

          (B) a judge may also designate a magistrate judge to
          conduct hearings, including evidentiary hearings, and
          to submit to a judge of the court proposed findings of
          fact and recommendations for the disposition, by a
          judge of the court, of any motion excepted in
          subparagraph (A), of applications for posttrial relief
          made by individuals convicted of criminal offenses and
          of prisoner petitions challenging conditions of
          confinement.
8                    MITCHELL V. VALENZUELA

magistrate judge is authorized, absent consent, only to issue
a report and recommendation to the district judge, who in turn
must undertake de novo review.2

    Mitchell argues that the magistrate judge overstepped his
authority by denying the motion to stay and abey his petition
pending exhaustion.3 We agree.

    2
   The terms “dispositive” and “nondispositive” do not appear in section
636. They do appear in Fed. R. Civ. P. 72, which implements section 636.
The notes to Rule 72 provide that at least subsection (b) of the Rule does
not apply to habeas cases, and one case of this court has so held. See
Cavanaugh v. Kincheloe, 

, 1449 (9th Cir. 1989). Another
Ninth Circuit opinion relies on Rule 72 in a habeas case. See 

–25.

     For present purposes, it does not matter whether Rule 72 directly
applies. The habeas rules provide for broad application of section 636.
See Rule 10, Federal Rules Governing § 2254 Cases (2015). The
“dispositive”/“nondispositive” terminology in Rule 72 reflects the
statutory distinction drawn in section 636 between the two principal roles
of magistrate judges. See Flam, 

at *2 (noting that
“[t]he textual basis for the distinction between dispositive and
non-dispositive motions is found in 28 U.S.C. § 636(b)(1)”). Before the
current Rule 72 was promulgated, the Supreme Court, citing the legislative
history of the Federal Magistrates Act, used the term “dispositive” in
describing those motions a magistrate judge is precluded from hearing and
determining under section 636. See United States v. Raddatz, 

, 673–76 (1980); 

(Stewart, J., dissenting). Thus, the
distinction derives from the statute and applies to habeas cases; Rule 72
simply implements the distinction for ordinary civil cases.
        3
     The state argued for the first time at oral argument that Mitchell
forfeited his right to appellate review of his contention that the magistrate
judge acted beyond his authority by failing to object to the denial of the
stay order before the district court. The state’s briefs do mention that
Mitchell did not appeal the denial of the stay to the district court, but only
to argue that section 636 was “complied with,” not to argue that the
question whether the statute was complied with was forfeited. The state’s
                    MITCHELL V. VALENZUELA                                9

    “[W]here the denial of a motion to stay is effectively a
denial of the ultimate relief sought, such a motion is
considered dispositive, and a magistrate judge lacks the
authority to ‘determine’ the matter.” S.E.C. v. CMKM
Diamonds, Inc., 

, 1260 (9th Cir. 2013) (citing

–17). By contrast, a motion to stay
is nondispositive where it “[does] not dispose of any claims
or defenses and [does] not effectively deny . . . any ultimate
relief sought.” 

fell into the latter, nondispositive
category.    In that case, a Securities and Exchange
Commission civil enforcement action, one of the defendants
moved to stay the civil proceedings until a related criminal
case had concluded. 

1254. A magistrate judge
denied the motion, and we held the magistrate judge within
his authority in doing so. 

The defendant had
“simply speculated that he might have stronger evidence to
support his position in the civil proceedings if he was able to
go through the criminal proceedings first.” 

we held, was insufficient to establish that the
denial of a stay would either “dispose of any claims or
defenses” or “effectively deny him any ultimate relief
sought.” 

judge was therefore empowered
to hear and determine the matter. 

is therefore waived. See Gallardo v. United States,

, 865 (9th Cir. 2014); Clem v. Lomeli, 

, 1182
(9th Cir. 2009). In any event, as the issue is one purely of law, and
concerns the appropriate exercise of federal judicial authority, even if the
issue were forfeited, we would exercise our discretion to decide the scope
of the magistrate judge’s authority as to Rhines stays. See Nguyen v.
United States, 

, 77–81 (2003); Ruiz v. Affinity Logistics Corp.,

, 1322 (9th Cir. 2012).
10               MITCHELL V. VALENZUELA

    In so holding, CMKM Diamonds cited the rule established
by our prior decision in Reynaga. The prisoner plaintiff in
Reynaga filed a pro se lawsuit under 42 U.S.C. § 1983,
alleging that the judge, district attorneys, and public defender
involved in his state criminal case had denied him a fair 

. The case was referred to a magistrate judge,
who determined that the defendants were immune from
money damages and that the injunction sought—namely early
release from prison—could only be pursued through habeas
corpus. 

judge thus ordered the action
stayed until the plaintiff exhausted his state remedies and
directed the clerk of court to administratively close the file.

on appeal that it was “clear” that, absent
consent, the magistrate judge’s stay order “was beyond his
authority.” 

Among other things, we said in
support of our conclusion, “[t]he Magistrate’s imposition of
the stay effectively denied Reynaga’s request for an
injunction,” and “the Magistrate’s order was in essence an
involuntary dismissal of Reynaga’s action.” 

Both a motion for injunctive relief and a motion for
involuntary dismissal are among the specifically enumerated
dispositive matters listed in section 636(b)(1)(A). 

Diamonds and Reynaga together, the
dispositive question for us is whether the motion to stay and
abey at issue here was effectively dispositive of a claim or
defense or of the ultimate relief sought. See Flam, 

at *2. As Rhines v. Weber, 

(2005),
makes clear, the answer is “yes.” Indeed, at oral argument
the state conceded that the stay denial in this case “was
tantamount to a dismissal” of the unexhausted claims, and
                  MITCHELL V. VALENZUELA                        11

there was “no way” Mitchell would be able to return to
federal court to assert those claims later.

    Under Rhines, a section 2254 habeas petitioner may seek
to stay and abey his petition while he exhausts his claims in
state court. This procedure addresses the difficulties posed by
the interaction of Rose v. Lundy, 

(1982), and the
Antiterrorism and Effective Death Penalty Act of 1996
(AEDPA).

    Lundy held that district courts were required to dismiss
without prejudice “mixed” section 2254 habeas
petitions—that is, those including both exhausted and
unexhausted 

. As Rhines explained,
Lundy held this “requirement of ‘total exhaustion’” before a
petition may proceed was required by “the interests of comity
and federalism.” 

–74. Fourteen years
later, Congress enacted AEDPA, which imposed a one-year
statute of limitations for the filing of a federal habeas petition.
While that limitations period is tolled “during the pendency
of a ‘properly filed application for State post-conviction or
other collateral review,’ [28 U.S.C.] § 2244(d)(2), the filing
of a petition for habeas corpus in federal court does not toll
the statute of limitations.” 

    Considering the implications of the enactment of AEDPA
for the continued viability of the Lundy rule requiring
dismissal of all mixed petitions, Rhines began from the
recognition that “[i]f a petitioner files a timely but mixed
petition in federal district court, and the district court
dismisses it under Lundy after the limitations period has
expired, this will likely mean the termination of any federal
review.” 

Rhines therefore authorized a
“‘stay-and-abeyance’ procedure,” under which the district
12                  MITCHELL V. VALENZUELA

court, “rather than dismiss the mixed petition,” may “stay the
petition and hold it in abeyance while the petitioner returns to
state court to exhaust his previously unexhausted claims.” 

“[s]tay and abeyance, if employed too
frequently, has the potential to undermine” AEDPA’s
purposes of reducing delay and requiring petitioners to
exhaust state remedies before coming to federal court, Rhines
instructed that “the district court should stay, rather than
dismiss, the mixed petition,” only “in limited circumstances,”
namely when three conditions are met: “[(1)] the petitioner
had good cause for his failure to exhaust, [(2)] his
unexhausted claims are potentially meritorious, and [(3)]
there is no indication that the petitioner engaged in
intentionally dilatory litigation tactics.” 

 4
   Under this circuit’s caselaw, a petitioner who has not exhausted all his
potential federal habeas claims has another mechanism available to him
to avoid the difficulties posed by the interaction of AEDPA’s statute of
limitations and Lundy’s rule—the three-step procedure outlined in Kelly
v. Small, 

(9th Cir. 2003), overruled on other grounds by
Robbins v. Carey, 

, 1149 (9th Cir. 2007). The Kelly
procedure permits “(1) a petitioner to amend his petition to delete any
unexhausted claims; (2) the court in its discretion to stay and hold in
abeyance the amended, fully exhausted petition, providing the petitioner
the opportunity to proceed to state court to exhaust the deleted claims; and
(3) once the claims have been exhausted in state court, the petitioner to
return to federal court and amend[] his federal petition to include the
newly-exhausted claims.” King v. Ryan, 

, 1139 (9th Cir.
2009). “[T]he Kelly procedure remains available after Rhines,” and,
unlike Rhines, “its availability is not premised upon a showing of good
cause.” 

As we explained in King, from the perspective of the
petitioner, the downside of the Kelly procedure is that there is no
assurance that the claims added to the petition after exhaustion will be
considered timely filed. 

Thus, compared to the Rhines
procedure, “Kelly is not only a more cumbersome procedure for
petitioners, but also a riskier one.” 

                 MITCHELL V. VALENZUELA                      13

    In light of Rhines, we conclude that a motion to stay and
abey section 2254 proceedings is generally (but not always)
dispositive of the unexhausted claims. Rhines acknowledged
“the gravity of th[e] problem” of the interaction of Lundy’s
total exhaustion rule with AEDPA’s one-year statute of
limitation, “and the difficulty it has posed for petitioners.”

. “[P]etitioners who come to federal
court with ‘mixed’ petitions run the risk of forever losing
their opportunity for any federal review of their unexhausted
claims,” 

a stay, they are presented with
two choices, each of which will ordinarily result in precluding
some or all of their claims: Either they may voluntary dismiss
unexhausted claims, proceeding on only the exhausted ones,
or they may decline to do so, leading to dismissal of the entire
petition. Either kind of dismissal would be, in form, without
prejudice. But, because the one-year statute of limitations is
not tolled while the federal petition is pending, Duncan v.
Walker, 

, 181 (2001), and because state
proceedings can be lengthy and unpredictable, in most cases
either option will mean that a petitioner will be barred from
federal review of some or all of his claims by the time he
exhausts them. If a petitioner voluntarily dismisses his
unexhausted claims, it is very likely that final state court
exhaustion of unexhausted claims will come too late to allow
the claims to be heard in federal court, whether because
(1) the statute of limitations period will have run on the
claims and they will not relate back to the filing of the
petition because they do not “arise[] from the same core of
operative facts as a claim contained in the original petition,”
Ford v. Gonzalez, 

, 1237 n.3 (9th Cir. 2012)
(internal quotation marks omitted); (2) the remaining federal
habeas petition will have been decided by the time the state
courts act on the new habeas claims, triggering the onerous
requirements for filing a second or successive habeas petition,
14                  MITCHELL V. VALENZUELA

28 U.S.C. § 2244(b); or (3) both. Similarly, if a petitioner
chooses to accept dismissal of the entire petition under Lundy,
he will very likely be barred from reasserting any of his
claims in federal court by AEDPA’s statute of limitations. In
either event, the result is the same as to the unexhausted
claims: The petitioner will lose the opportunity ever to
present those claims to a federal habeas court.5 Thus, in this
case, like Reynaga and unlike CMKM Diamonds, the
magistrate judge’s order was effectively dispositive of the
unexhausted claims and, therefore, beyond his authority.


     5
      It is, of course, possible that in some cases a petitioner could
successfully return to federal court after he exhausts his claims, even
without a stay. For example, a petitioner whose petition is dismissed
under Lundy could have time remaining on the AEDPA statute of
limitations; that period is tolled during the pendency of “a properly filed
application for State post-conviction or other collateral review.”
28 U.S.C. § 2244(d)(2) (emphasis added). Thus, he might exhaust his
remaining claims and file a second habeas petition, all within the statute
of limitations. But, because a petition may be deemed not “properly” filed
after years of litigation, see, e.g., Evans v. Chavis, 

, 200
(2006), it is generally impossible for a petitioner to know in advance
whether he will be successful in bringing his dismissed claims back to
federal court. Exacerbating this uncertainty in the context of this case is
“California’s unusual system of independent collateral review” in which
“a prisoner seeks review of a lower court’s denial of relief by filing an
original petition for habeas corpus in the reviewing court,” rather than an
appeal, and a “petition is timely filed if it is filed within a ‘reasonable
time,’” rather than within a set period of time. Banjo v. Ayers, 

, 968 (9th Cir. 2010). Because of this ex ante danger that the petitioner
will not be granted the benefit of statutory tolling for some unforeseen
reason, the denial of a motion to stay and abey a habeas petition should be
treated as presumptively dispositive of unexhausted claims.

    We do not, however, foreclose the possibility that the state could
establish, in particular cases, that the denial of such a motion was not
dispositive under the circumstances. The state has not made nor attempted
any such showing here.
                 MITCHELL V. VALENZUELA                     15

    Indeed, we have previously recognized, in similar but not
identical circumstances, that the interaction of AEDPA’s
statute of limitations and Lundy’s total-exhaustion rule
constrains the authority of magistrate judges. Hunt v. Pliler
considered a magistrate judge’s order holding a habeas
petition mixed and warning that, unless the petitioner sought
leave to file an amended petition without the unexhausted
claims, the court would dismiss the petition in full under

. The petitioner refused to do so
and, after a “tortuous procedural hegira,” the district court
ultimately dismissed the petition with prejudice. 

We vacated the court’s judgment, citing, in part,
the court’s and the magistrate judge’s “fail[ure] to comply
with § 636 and Rule 72, depriving Hunt of the right to de
novo review by the district court of the magistrate judge’s
pivotal determination that the [petition] contained
unexhausted claims.” 

That determination was
pivotal, we explained, because it “required Hunt to forfeit the
claims [the magistrate judge] found unexhausted or face
dismissal of the entire petition, effectively with prejudice
because any newly filed petition would be barred by
AEDPA’s one-year statute of limitations.” 

(citing
28 U.S.C. § 2244(d)); see also 

the
magistrate judge’s order could “hardly be considered
equivalent to a dismissal with leave to amend because [it]
compelled Hunt to abandon claims he contended had been
exhausted or face dismissal of his entire petition with
prejudice”). We therefore held that the magistrate judge’s
determination, purportedly on his own authority, that the
petition was mixed “exceeded his statutory authority.” 

different from this case in that the petitioner in
Hunt did not seek a stay pending exhaustion in state court, 

and Mitchell did not affirmatively contest that his
16               MITCHELL V. VALENZUELA

petition was mixed. But Hunt held that the magistrate judge
could not hear and determine the question whether the
petition was mixed because the resolution of that issue would
have dispositive effect as to the unexhausted claims: If the
petition was mixed, Hunt recognized, the choices confronting
the petitioner would be to either “abandon” his purportedly
unexhausted claims or else face “dismissal of the entire
petition, effectively with prejudice,” because of AEDPA’s
statute of limitations. 

. The stay-and-abey motion
at issue here was, as explained above, dispositive for the same
reason. In the shadow of Lundy and AEDPA, the denial of a
Rhines stay, like a determination that the petition is mixed,
generally amounts to dismissal of the unexhausted claims
with prejudice.

    Finally, Flam recently held that a motion to remand a
removed case to state court is a dispositive matter under our
“functional approach.” Flam, 

at *2–3.
Flam agreed with several other circuits that “such a remand
order is ‘dispositive insofar as proceedings in the federal
court are concerned,’” because “such an order ‘preclusively
determines the important point that there will not be a federal
forum available to entertain a particular dispute.’” 

(quoting In re U.S. Healthcare, 

, 146 (3d Cir.
1998)). Because remand orders “put litigants out of federal
court,” Flam held, they are dispositive in the relevant sense.

same is true in this context. The denial of a
motion to stay and abey is “dispositive insofar as proceedings
in the federal court are concerned,” because “such an order
preclusively determines the important point that there will not
be a federal forum available to entertain” the petitioner’s
unexhausted claims. 

marks omitted).
                 MITCHELL V. VALENZUELA                     17

    In sum, the magistrate judge in this case had no authority
to hear and determine the motion to stay and abey habeas
proceedings to permit exhaustion of claims. He was, instead,
required to submit a report and recommendation to the district
court on that matter, for de novo review.

    Because, “the procedure leading to [the] dismissal” of this
habeas petition “failed to comply with § 636,” 

, we vacate the district court’s judgment and remand
for further proceedings, guided by the principle that “we
cannot countenance a magistrate judge’s unauthorized”
orders, Allen v. Meyer, 

, 869 (9th Cir. 2014), nor
the results flowing from such orders, cf. 

.

    The magistrate judge should have issued a report and
recommendation as to the motion to stay and abey. The
district court should therefore undertake, on remand, de novo
review as to whether such a stay was warranted at the time of
the magistrate judge’s order. The district court may consider
the magistrate judge’s order on the stay as a report and
recommendation, in which case the court should afford the
parties an opportunity to lodge objections.               See

(remanding “for the
district court to apply de novo review . . . “treat[ing] the
magistrate judge’s ‘order’ as proposed findings and
recommendations”). If the district court concludes that no
stay was warranted, then the magistrate judge’s unauthorized
action was harmless, and the district court may reimpose its
previous order. See 

stay was warranted, then the district court must
determine what prejudice the petitioner suffered as a result.
18                   MITCHELL V. VALENZUELA

The pertinent question is: Would the case have progressed
differently had a stay been granted, and, if so, how?

    The magistrate judge’s unauthorized denial of the motion
to stay and abey proceedings led directly to Mitchell’s
voluntary dismissal of two of his claims. The magistrate
judge expressly linked the two issues in his order, noting that,
because the petition was not eligible for a Rhines stay, unless
Mitchell voluntarily dismissed his unexhausted claims, the
magistrate judge would recommend that the state’s motion to
dismiss be granted. Mitchell did so shortly thereafter. But
for the magistrate judge’s unauthorized action, if a stay was
warranted, the case would have been stayed while Mitchell
sought to exhaust the two unexhausted claims. Thus, if a stay
should have been granted, the unauthorized stay denial
caused Mitchell to lose the opportunity for a merits review on
habeas of those two claims. Consequently, if the district
court determines that a stay was warranted at the time, it
should either stay the case under Rhines, if those claims
remain unexhausted, or, if now exhausted, proceed to
consider those claims as if they had never been dismissed.6




 6
    With the petition not stayed and the claims dismissed, Mitchell could
well have concluded that exhaustion would have been futile with regard
to the viability of those claims in federal court. Indeed, it is quite likely
that he recognized what the state conceded in oral argument: The denial
of the stay motion was “tantamount to a dismissal” of the unexhausted
claims with prejudice, as there was “no way” Mitchell would be able to
return to federal court to assert them.
                   MITCHELL V. VALENZUELA                             19

    We vacate the judgment of the district court and remand
for proceedings consistent with this opinion.7

      VACATED AND REMANDED.




  7
    Because we remand on this basis, we do not decide the other aspects
of the certified question. Nor do we reach Mitchell’s uncertified issues,
as they address the merits of the stay denial and of the three claims
addressed by the district court.