                   FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

ARTHUR ROBBINS, III,                          No. 05-17131
            Petitioner-Appellant,
               v.                               D.C. No.
                                             CV-04-06337-OWW
TOM L. CAREY,
                                                 OPINION
            Respondent-Appellee.
                                         
        Appeal from the United States District Court
            for the Eastern District of California
        Oliver W. Wanger, District Judge, Presiding

                 Argued and Submitted
       November 17, 2006—San Francisco, California

                     Filed March 12, 2007

     Before: J. Clifford Wallace and Sidney R. Thomas,
     Circuit Judges, and David A. Ezra,* District Judge.

                   Opinion by Judge Thomas




  *The Honorable David A. Ezra, United States District Judge for the
District of Hawaii, sitting by designation.

                               2937
                     ROBBINS v. CAREY                 2939


                       COUNSEL

David M. Porter (argued) and Daniel J. Broderick, Office of
the Federal Defender, Sacramento, California, for the
petitioner-appellant.
2940                   ROBBINS v. CAREY
Jeanne R. Wolfe (argued) and Bill Lockyer, Robert R. Ander-
son, Mary Jo Graves, Stephen G. Herndon, and Mark A.
Johnson, Office of the Attorney General of the State of Cali-
fornia, Sacramento, California, for the respondent-appellee.


                          OPINION

THOMAS, Circuit Judge:

   In this appeal, we consider whether, in the absence of a
request from an unrepresented petitioner, a district court is
required to consider, sua sponte, the option of staying and
abeying a petition for a writ of habeas corpus when the peti-
tioner has filed a “mixed” petition consisting of both
exhausted and unexhausted claims. We hold that such a
requirement would conflict with Pliler v. Ford, 542 U.S. 225
(2004), and Rhines v. Weber, 544 U.S. 269 (2005), and we
affirm the judgment of the district court.

                               I

   On October 13, 1999, in a California state court, Robbins
pled no contest to possession with intent to sell crack cocaine.
He had been arrested after a bag of cocaine had been found
on the passenger-side floorboard of the car he was driving.
Because Robbins had two prior convictions which the state
court declined to excise, the court sentenced him to prison for
25 years to life under California’s “three strikes” law. Rob-
bins appealed, and his appointed appellate attorney filed a
“People v. Wende brief” that simply asked the court to con-
duct an independent review of the record, without raising any
specific issues. See People v. Wende, 600 P.2d 1071 (Cal.
1979). Dissatisfied with his appellate representation, Robbins
requested and was denied appointment of new counsel, but he
raised issues of his own in a letter brief.
                       ROBBINS v. CAREY                    2941
   After the state appellate court affirmed his conviction, Rob-
bins filed a petition for review with the California Supreme
Court. The thrust of Robbins’ argument was that the arresting
officer did not have probable cause to pull over the car Rob-
bins was driving. Robbins argued that the arresting officer
lied when he testified that he discovered Robbins had a sus-
pended license prior to the stop; rather, the arresting officer
learned of the suspended license only after the stop and the
discovery of the cocaine. Under this latter scenario, Robbins
argued, there was no probable cause to stop the car and the
fruits of the search would be tainted. Robbins’ state court
petition also argued that his appellate counsel was ineffective
for failing to raise the Fourth Amendment defense and the
contradictory testimony of the arresting officer, and that the
appellate court’s review was objectively unreasonable.

   The California Supreme Court denied his petition for
review, after which Robbins filed his federal habeas petition
on September 30, 2004. His amended habeas petition, filed on
December 30, 2004, sought relief on four grounds: (1) trial
counsel was ineffective for failing to object to the officer’s
contradictory statements; (2) his conviction was obtained
through evidence that should have been excluded; (3) appel-
late counsel was ineffective for failing to appeal any issues,
such as trial counsel’s ineffectiveness or the unlawful search
and arrest; and (4) it was objectively unreasonable for the
state courts to summarily deny his arguments on appeal. The
Warden moved for dismissal, arguing that Robbins failed to
exhaust these claims in state court, and on July 12, 2005, the
magistrate judge issued a report recommending the dismissal
of Robbins’ habeas petition because the ineffective assistance
of trial counsel claim had not been exhausted in state court.
The magistrate judge also recommended that Robbins’ fourth
claim be dismissed because it failed to state a cognizable fed-
eral claim.

   The magistrate judge’s report stated that both parties had
thirty days in which to file objections to the report, and that
2942                   ROBBINS v. CAREY
otherwise the report would be submitted to the district court
for review. The magistrate judge gave Robbins the option of
withdrawing his unexhausted claims within thirty days to
allow him to proceed with the exhausted claims; the magis-
trate judge explained that if Robbins did not withdraw the
unexhausted claims, the entire “mixed” petition would be dis-
missed without prejudice to allow Robbins to seek exhaustion
before refiling his federal petition. The magistrate judge did
not mention that the one-year limitations period imposed by
the Antiterrorism and Effective Death Penalty Act of 1996
(“AEDPA”), 28 U.S.C. § 2244(d), had by then expired five
months earlier, in February of 2005, and thus that if Robbins’
federal petition were dismissed, he would be unable to re-file
in federal court after exhausting his claims in state court. Nor
did the magistrate judge advise Robbins of the stay-and-
abeyance procedure at issue here. Following the issuance of
the report, Robbins did not file any objections and did not
request a stay and abeyance or a withdrawal of his unex-
hausted claims. As a result, the district court adopted in full
the magistrate judge’s report and dismissed Robbins’ habeas
petition.

   We have jurisdiction to review the district court’s denial of
a petition for habeas corpus pursuant to 28 U.S.C. § 2253(a).
We issued a certificate of appealability (“COA”) on Robbins’
claim that Kelly v. Small, 315 F.3d 1063 (9th Cir. 2003),
required the district court to consider sua sponte the stay-and-
abeyance procedure. 28 U.S.C. § 2253(c). Our review is lim-
ited to that question. Id.

   We review the district court’s dismissal of a mixed habeas
petition de novo. Olvera v. Giurbino, 371 F.3d 569, 572 (9th
Cir. 2004). We also review pure legal questions and mixed
questions of law and fact de novo when the state court has not
reached the merits of the question. Pirtle v. Morgan, 313 F.3d
1160, 1167 (9th Cir. 2002).
                       ROBBINS v. CAREY                     2943
                               II

   As a threshold matter, we must determine whether Robbins
properly preserved his right to appeal the district court’s deci-
sion. The Warden argues that Robbins waived this right by
failing to file objections to the magistrate judge’s report
within the thirty days provided by the magistrate judge.
Indeed, Robbins filed no objections to the report at all, before
or after the thirty-day deadline. When no objections were
filed, the district court adopted the magistrate judge’s recom-
mendation in full and dismissed Robbins’ habeas petition
because it contained unexhausted claims. Robbins then filed
a timely notice of appeal.

   [1] “The failure to object in the district court to a magis-
trate’s finding of fact waives a challenge to that finding.”
United States v. Torf, 357 F.3d 900, 910 (9th Cir. 2004) (as
amended) (citing Turner v. Duncan, 158 F.3d 449, 455 (9th
Cir. 1998) (as amended)). However, the failure to object to a
magistrate judge’s conclusions of law does not automatically
waive a challenge on appeal. Turner, 158 F.3d at 455.
Because determinations of law by the magistrate judge are
reviewed de novo by both the district court and this court,
“the failure to object would not, standing alone, ordinarily
constitute a waiver of the issue.” Martinez v. Ylst, 951 F.2d
1153, 1156 (9th Cir. 1991). The failure to object to a magis-
trate judge’s conclusion of law “is a factor to be weighed in
considering the propriety of finding waiver of an issue on
appeal.” Id. In Martinez, we held that when a party has failed
both to object to a magistrate judge’s legal findings and to
raise the issue in its opening appellate brief — raising the
issue in a reply brief instead — “waiver is appropriate unless
there are circumstances suggesting that it will work a substan-
tial inequity.” Id. at 1157.

   [2] Robbins’ arguments on appeal implicate his failure to
object to the magistrate judge’s legal conclusions concerning
state court exhaustion and lack of a federal claim. He does not
2944                       ROBBINS v. CAREY
challenge the magistrate judge’s factual findings. Unlike the
party in Martinez, Robbins did raise his arguments in his
opening brief to this court. Thus, he is entitled to the “ordi-
nary” presumption that failure to object to the magistrate
judge’s report, “standing alone,” does not constitute waiver.
See id. at 1156. Moreover, we granted Robbins a COA on an
issue that was not and could not have been addressed in the
magistrate judge’s report or, indeed, by the district court,
because had Robbins been aware of the possibility of the stay-
and-abeyance procedure while his case was pending in the
district court, he would have requested it outright. The
essence of his appeal is that, acting pro se, he was not aware
of the stay-and-abeyance procedure and did not request it,
thus requiring the district court to consider it without prompt-
ing. Robbins’ failure to object to the magistrate judge’s report
is, therefore, irrelevant to the claim before us.

                                   III

   We conclude that a district court is not required sua sponte
to consider whether it should stay and abey a mixed habeas
petition. “Mixed” petitions are those habeas petitions consist-
ing of both exhausted and unexhausted claims. See Rose v.
Lundy, 455 U.S. 509, 510 (1982). The Supreme Court has
held that district courts generally1 must dismiss such mixed
petitions, “leaving the prisoner with the choice of returning to
state court to exhaust his claims or of amending or resubmit-
ting the habeas petition to present only exhausted claims to
the district court.” Id. This total exhaustion requirement pre-
sented significant difficulties once Congress enacted AEDPA
in 1996, imposing a one-year statute of limitations on the fil-
ing of habeas petitions in federal court. 28 U.S.C. § 2244(d).
  1
    The Supreme Court recently recognized an exception to the dismissal
requirement, permitting district courts to stay mixed petitions in certain
circumstances while the petitioner exhausts his unexhausted claims.
Rhines, 544 U.S. at 278; Jackson v. Roe, 425 F.3d 654, 659-61 (9th Cir.
2005) (discussing the Rhines holding).
                       ROBBINS v. CAREY                     2945
See Rhines, 544 U.S. at 274-75. The AEDPA limitations
period is tolled while a prisoner seeks collateral review in a
state court, but not while the prisoner is in federal court. 28
U.S.C. § 2244(d)(2); Rhines, 544 U.S. at 274-75.

   The Supreme Court has recognized that the interplay
between Lundy and AEDPA means that “petitioners who
come to federal court with ‘mixed’ petitions run the risk of
forever losing their opportunity for any federal review of their
unexhausted claims.” Id. at 275. In other words, if a prisoner
files a timely, mixed petition and the district court makes a
Lundy ruling after the one-year limitations period has run, the
prisoner is precluded from filing a new federal habeas petition
after exhausting those unexhausted claims.

   In Calderon v. United States District Court (“Taylor”), we
approved one solution to that conundrum, a three-step stay-
and-abeyance procedure in which: (1) the prisoner amends his
mixed petition to remove the unexhausted claims; (2) the dis-
trict court stays and holds in abeyance the amended and fully
exhausted petition; and (3) the prisoner re-amends his petition
to add the newly-exhausted claims after litigating them in
state court. 134 F.3d 981, 986 (9th Cir. 1998). Kelly v. Small
affirmed that procedure and held that district courts must con-
sider it sua sponte regardless of whether the prisoner raises it,
specifying that the stay-and-abeyance procedure “is particu-
larly appropriate when an outright dismissal will render it
unlikely or impossible for the petitioner to return to federal
court within the one-year limitation period.” 315 F.3d 1063,
1070 (9th Cir. 2003) (as amended); see also Smith v. Ratelle,
323 F.3d 813, 818 (9th Cir. 2003); Guillory v. Roe, 329 F.3d
1015, 1017 (9th Cir. 2003).

   [3] In Ford v. Hubbard, we held that, when faced with a
pro se habeas petitioner, “the district court was obligated to
inform him of his options with respect to his mixed habeas
petitions: to advise him that it would have the power to con-
sider his stay motions only if he opted to proceed with his
2946                   ROBBINS v. CAREY
exhausted claims and dismiss the unexhausted claims.” 330
F.3d 1086, 1099 (9th Cir. 2003) (as amended), rev’d sub nom.
Pliler v. Ford, 542 U.S. 225 (2004). We also held that the dis-
trict court was obligated to inform the petitioner that
AEDPA’s statute of limitations period had run and that he
would be barred from seeking habeas relief in federal court if
he failed to amend his petitions or dismissed them in order to
exhaust the unexhausted claims. Id. at 1102.

   [4] The Supreme Court reversed those holdings in Pliler.
542 U.S. at 234. The Supreme Court specifically declined to
address “the propriety of [the Ninth Circuit’s] stay and abey-
ance procedure,” but held that “federal district judges are not
required to give pro se litigants these two warnings.” Id. at
231. Robbins interprets this language as taking issue only
with the giving of two warnings. We do not believe Pliler can
be read so narrowly. Pliler extends beyond the giving of two
warnings to pro se litigants because district courts “have no
obligation to act as counsel or paralegal to pro se litigants,”
id., and because “ ‘the Constitution [does not] require judges
to take over chores for a pro se defendant that would normally
be attended to by trained counsel as a matter of course,’ ” id.
(quoting McKaskle v. Wiggins, 465 U.S. 168, 183-84 (1984)).
The Supreme Court further expressed concern that requiring
district courts to advise pro se litigants “would undermine dis-
trict judges’ role as impartial decisionmakers.” Id. Later in the
opinion, the Supreme Court explained that “nothing in Rose
[v. Lundy] . . . suggests that district judges give specific
advisements as to the availability and wisdom of the[ ]
options” faced by a petitioner with a mixed petition. Id. at
233.

   [5] Thus, although the Taylor stay-and-abeyance option
remains in place for district courts, Pliler makes it clear that
district courts are not required to consider sua sponte the stay-
and-abeyance procedure. Such a mandatory action by the trial
judge falls within the set of “chores” targeted by the Supreme
Court in Pliler. See also Brambles v. Duncan, 412 F.3d 1066,
                         ROBBINS v. CAREY                        2947
1070-71 (9th Cir. 2005) (following Pliler, the district court
had no obligation to inform habeas petitioner that the stay-
and-abeyance procedure was available). Therefore, Pliler
effectively overruled any requirement to the contrary con-
tained in Kelly v. Small and its progeny.

   Robbins argues that there is a distinction between Kelly’s
requirement that a court must “consider” the procedure and
Pliler’s holding that courts are not required to issue warnings
about the use of the procedure. However, there is no differ-
ence between “considering” a procedure and notifying a party
about the possibility of that procedure, because in both cases
the district court must sua sponte inform the party of the pro-
cedure, partly so that the petitioner may decide which option
to pursue. The district court cannot merely “consider” the
stay-and-abeyance option on its own; rather, it must inform
both parties of its possible use to enable them to provide the
information the court needs to exercise its discretion over
whether to stay and abey the petition.

   The Supreme Court’s decision in Rhines v. Weber, 544
U.S. 269 (2005), is not to the contrary and does not detract
from the holding of Pliler. There, the Supreme Court
addressed the propriety of staying a mixed petition while a
petitioner exhausts his unexhausted claims in state court.
Rhines, 544 U.S. at 271. The Court upheld the procedure but
found that it “should be available only in limited circum-
stances.” Id. at 277. Specifically, the Court said it was appro-
priate only when (1) good cause exists for petitioner’s failure
to exhaust; (2) petitioner’s unexhausted claims are not
“plainly meritless”; and (3) there is no indication that peti-
tioner engaged in “abusive litigation tactics or intentional
delay.” Id. at 277-278. Thus, Rhines merely approved a version2
of the stay-and-abeyance procedure. Although, as Robbins
  2
   See Jackson, 425 F.3d at 661, for a discussion of the differences
between the stay-and-abeyance procedure described in Rhines and that of
Kelly.
2948                        ROBBINS v. CAREY
argues, Rhines may have endorsed the procedure, there is no
indication that its endorsement was so hearty that it condoned
a requirement that district courts must consider the procedure
sua sponte. Such a requirement would be inconsistent with
Pliler, and there is no indication in Rhines that the Supreme
Court intended to revise Pliler, much less overrule it.
                               IV
   [6] In light of Pliler v. Ford, we conclude that the district
court was not required to consider, sua sponte, the stay-and-
abeyance procedure. To the extent that Kelley v. Small and its
progeny suggest otherwise, those cases are overruled.3 We
affirm the district court’s judgment dismissing Robbins’
mixed petition. We need not, and do not, reach any other issue
urged by the parties.4
   AFFIRMED.
  3
     Ordinarily, panels cannot overrule a circuit precedent; that power is
reserved to the circuit court sitting en banc. United States v. Washington,
872 F.2d 874, 880 (9th Cir. 1989) (as amended). As an exception to this
general rule, we have held that where an intervening higher authority has
issued an opinion that is “clearly irreconcilable” with our prior circuit pre-
cedent, a panel is free to act disregarding that precedent. Miller v. Gam-
mie, 335 F.3d 889, 893, 900 (9th Cir. 2003) (en banc).
   4
     Because we conclude that the district court in this case was under no
obligation to consider the stay-and-abeyance procedure sua sponte, we do
not reach the Warden’s argument that Robbins did not meet the new stan-
dards laid out in Rhines for applying the procedure. We also do not
address whether the Rhines requirements apply to the specific type of stay-
and-abeyance procedure at issue in Kelly, see Jackson, 425 F.3d at 661,
and we do not alter the “strong preference” in favor of granting the Kelly
procedure, if requested by the petitioner, “when an outright dismissal will
render it unlikely or impossible for the petitioner to return to federal court
within the one-year limitation period,” Kelly, 315 F.3d at 1070. Nor do we
reach Robbins’ uncertified argument that all claims in his habeas petition
were exhausted and thus that his petition was not “mixed.” Finally, we
deny Robbins’ motion before this court to hold his habeas petition in abey-
ance while he seeks exhaustion in state court. Because we affirm the dis-
trict court’s dismissal of his petition, this motion is now moot.
