FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

DONALD E. DAWSON,                        No. 06-56454
            Petitioner-Appellant,           D.C. No.
               v.
                                       CV-04-00431-SGL
JOHN MARSHALL,                           ORDER AND
            Respondent-Appellee.          AMENDED
                                          OPINION

       Appeal from the United States District Court
           for the Central District of California
       Stephen G. Larson, District Judge, Presiding

                Argued and Submitted
        December 17, 2008—Pasadena, California

                 Filed February 9, 2009
                Amended March 6, 2009

 Before: Cynthia Holcomb Hall, Diarmuid F. O’Scannlain,
          and Richard A. Paez, Circuit Judges.

              Opinion by Judge O’Scannlain




                          2809
                     DAWSON v. MARSHALL                     2811




                          COUNSEL

Peter R. Afrasiabi, Turner Green LLP, Costa Mesa, Califor-
nia, argued the cause for the appellant and filed the briefs.

Heather M. Heckler, Deputy Attorney General for the State of
California, Sacramento, California, argued the cause for the
appellee and filed the brief. Edmund G. Brown, Jr., Attorney
General of the State of California; Dane R. Gillette, Chief
Assistant Attorney General; Julie L. Garland, Senior Assistant
Attorney General; and Jennifer A. Neill, Supervising Deputy
Attorney General; were also on the brief.


                           ORDER

  The opinion filed on February 9, 2009, is amended as fol-
lows:

   At page 1463 of the slip opinion, line 8, after the sentence
concluding “ ‘findings or recommendations to which objec-
tion is made,’ ” insert a footnote 2, reading 

  Future petitions for rehearing will not be entertained.

  It is so ORDERED.


                          OPINION

O’SCANNLAIN, Circuit Judge:

  May an Article III judge decide a habeas petition on which
he had issued findings and recommendations in his prior
capacity as a magistrate judge?

                                I

   Donald Dawson is serving a term of 26 years to life for the
first degree murder of his ex-wife in the mid-1980s. In July
of 2001, Dawson sought parole from the California Board of
Paroles, which found him unsuitable. After unsuccessfully
petitioning for a writ of habeas corpus in California state court
to overturn the board’s denial, Dawson filed a habeas petition
in the Central District of California pursuant to 28 U.S.C.
§ 2254.

   In 2005, then-Magistrate Judge Stephen Larson issued a
Report and Recommendation (“R&R”) in Dawson’s habeas
case, recommending denial. Dawson filed objections and
sought review before the assigned district judge under 28
U.S.C. § 636. The following year, Judge Larson was commis-
sioned by President George W. Bush as a United States Dis-
trict Judge for the Central District of California and was
                           DAWSON v. MARSHALL                              2813
reassigned Dawson’s case in his new capacity. In August of
2006, now-District Judge Larson issued an order and judg-
ment dismissing Dawson’s petition. In that order, Judge Lar-
son did not adopt the R&R he had written as a magistrate
judge, but rather issued a separate 18-page order in which he
did not reference his previous R&R.

   Dawson appealed, and ultimately we issued a memorandum
disposition affirming the denial of Dawson’s habeas petition.
Dawson then petitioned for panel rehearing. We granted
rehearing and invited additional briefing on whether Judge
Larson’s role as both magistrate judge and district judge war-
rants reversal and reassignment of the case to another district
judge. By separate order, we have withdrawn our earlier
memorandum disposition, which we replace with this opinion.1

                                       II

   [1] Section 636 outlines the jurisdiction, powers, and tem-
porary assignments of magistrate judges. The statute permits,
but does not require, a district judge to designate a magistrate
judge to submit proposed findings or recommendations for the
disposition of a case. If that happens,“any party may serve
and file written objections to such proposed findings and rec-
ommendations as provided by rules of court. A judge of the
court shall make a de novo determination of those portions of
the report or specified proposed findings or recommendations
to which objection is made.”2 28 U.S.C. § 636(b)(1)(C)
(emphasis added).
  1
     In a concurrently filed memorandum disposition, we address Dawson’s
additional challenges to the district court’s decision. See Dawson v. Mar-
shall, No. 06-56454 (9th Cir. Feb. 9, 2009).
   2
     We note that review by a district judge of a magistrate judge’s findings
or recommendations is not the same thing as review by an appellate judge
of a trial judge’s judgment. Magistrate and district judges are both judges
at the trial, rather than appellate level, so that a district judge does not hear
an “appeal” from “judgments” of a magistrate judge. The rule governing
appellate review of trial courts is simple and absolute. “No judge shall
hear or determine an appeal from the decision of a case or issue tried by
him.” 28 U.S.C. § 47. Nothing in our opinion affects or changes that rule.
2814                  DAWSON v. MARSHALL
   [2] Thus, even though the district judge need not refer a
case to a magistrate judge, see 

(stating a
[district] judge “may” designate a magistrate judge to submit
a proposed findings and recommendation to the district
judge), once he does and once there is a proper objection, the
district judge “shall make a de novo determination,” 

As we said of this statute in a related context,
“[b]y utilizing the words ‘shall’ and ‘may’ in consecutive sen-
tences, Congress clearly indicated that district courts are
required to make a de novo determination of the portions of
the magistrate judge’s report to which a party objects.” United
States v. Howell, 

, 622 (9th Cir. 2000). So, too,
with the use of ‘shall’ and ‘may’ in close proximity. Read this
way, § 636 straightforwardly balances judicial efficiency and
due process. See Roell v. Withrow, 

, 588-89
(2003) (internal quotation marks and citations omitted) (“In
giving magistrate judges case-dispositive civil authority, Con-
gress hoped to relieve the district courts’ mounting queue of
civil cases and thereby improve access to the courts for all
groups. At the same time, though, Congress meant to preserve
a litigant’s right to insist on trial before an Article III district
judge insulated from interference with his obligation to ignore
everything but the merits of a case.”).

                                III

   Dawson argues that the district court violated the require-
ment of § 636 that it make a “de novo determination” of the
magistrate judge’s recommendations. The meaning of de novo
review, according to Dawson, precludes the de novo reviewer
—the district judge—from being the same person as the one
whose work is being reviewed—the magistrate judge. This
denial of full de novo review, he adds, amounts to a denial of
his right to have an Article III judge hear his case.

                                 A

  [3] De novo review means that the reviewing court “do[es]
not defer to the lower court’s ruling but freely consider[s] the
                     DAWSON v. MARSHALL                    2815
matter anew, as if no decision had been rendered below.”
United States v. Silverman, 

, 576 (9th Cir. 1988).
Dawson argues that Judge Larson could not have performed
such a review because no one can consider anew one’s own
work. He cites no authority for this proposition. We have
never suggested such an exacting psychological precision,
although, of course, a situation like the one before us is rare.
Nor does the statutory language require that the magistrate
judge and the district judge be different people.

   [4] Dawson would have us draw an analogy between the
respective roles of the magistrate and the district judge and
the roles of an associate and partner in a law firm. Just as an
associate may not be as thorough and careful as the partner
would be because he knows that the partner must make the
final decision, Dawson urges, so the magistrate judge’s analy-
sis is not complete because he leans on the backstop of the
district judge. But even if we accepted the analogy, it would
cut the other way. That is, it explains why the same person
would perform a different kind of review in his capacity as a
district judge than he did as a magistrate judge, despite his
familiarity with the case. Indeed, in this case District Judge
Larson did not simply adopt his previous R&R, but produced
a separate, 18-page opinion.

                               B

   [5] As far as the strictures of the Constitution are con-
cerned, the crucial fact is that an Article III judge reviewed
the case and rendered judgment. As the government points
out, reference to a magistrate judge is entirely discretionary.
See 28 U.S.C. § 636(b)(1)(A)-(B) (“a judge may designate”
(emphasis added)). The litigant has no right to a magistrate
judge but only to an Article III judge. See Commodity Futures
Trading Comm’n v. Schor, 

, 848 (1986) (“Article
III . . . safeguard[s] litigants’ right to have claims decided
before judges who are free from potential domination by other
2816                 DAWSON v. MARSHALL
branches of government.” (internal quotation marks and cita-
tion omitted)).

   [6] Thus, this case is substantively indistinguishable from
the situation in which no magistrate judge ever made recom-
mendations, but instead the case remained with the district
judge for disposition, without the magistrate judge’s R&R.
The latter case, of course, would pose no problem. The only
difference here is the depth of Judge Larson’s pre-existing
familiarity with the case.

                               C

   [7] Although Judge Larson’s role in this case violated no
law and denied Dawson no right, the practice of district
judges reviewing cases on which they previously sat as mag-
istrate judges is not desirable. Although Judge Larson’s role
in this case was proper, there is a problem of appearances.
Therefore, in our supervisory capacity over the district courts
of this Circuit, we suggest that district courts avoid assigning
new district judges to cases they handled as magistrates. See
Thomas v. Arn, 

, 146-47 (1985) (“[The Supreme]
Court has acknowledged the power of the courts of appeals to
mandate procedures deemed desirable from the viewpoint of
sound judicial practice although in nowise commanded by
statute or by the Constitution.” (internal quotation marks
omitted)); United States v. Rubio-Villareal, 

,
298, (9th Cir. 1992) (“In prescribing a rule applicable only to
the conduct of personnel within the judicial branch, we act in
a sphere where the scope of our supervisory power is at its
apex.” (internal quotation marks omitted)).

                              IV

  For the foregoing reasons, the district court’s dismissal of
Dawson’s habeas petition is

  AFFIRMED.