                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

ROBERT MORRIS FENENBOCK,                 No. 11-15880
             Petitioner-Appellant,          D.C. No.
               v.                        2:97-cv-01731-
DIRECTOR OF CORRECTIONS FOR               LKK-CHS
CALIFORNIA,                              ORDER AND
             Respondent-Appellee.         AMENDED
                                           OPINION

      Appeal from the United States District Court
          for the Eastern District of California
   Lawrence K. Karlton, Senior District Judge, Presiding

                  Argued and Submitted
        April 16, 2012—San Francisco, California

                  Filed May 24, 2012
                Amended August 30, 2012

 Before: Mary M. Schroeder, Diarmuid F. O’Scannlain, and
             Susan P. Graber, Circuit Judges.

                 Opinion by Judge Graber




                          10255
10258       FENENBOCK v. DIRECTOR OF CORRECTIONS




                         COUNSEL

Jolie Lipsig, Sacramento, California, for the petitioner-
appellant.

Glenn R. Pruden, Supervising Deputy Attorney General, San
Francisco, California, for the respondent-appellee.


                          ORDER

   The opinion filed on May 24, 2012, slip opinion page 5701,
is amended as follows:

   On slip opinion page 5718, replace footnote 12 with the
following:

       In briefing and at oral argument, the parties agreed
    that the last reasoned state court opinion addressed
    the constitutional question. In our view, that opinion
            FENENBOCK v. DIRECTOR OF CORRECTIONS         10259
    resolved Petitioner’s claim on only state evidentiary
    grounds. See Williams v. Cavazos, 646 F.3d 626,
    636-37 (9th Cir. 2011), cert. granted, 132 S. Ct.
    1088 (2012). But it is possible that the state supreme
    court later implicitly ruled on the constitutional
    claim, albeit without explanation, when it decided
    Petitioner’s habeas claims. See Richter, 131 S. Ct. at
    784; see also Williams, 646 F.3d at 636.

       Regardless, we need not resolve the question
    because Petitioner’s claims would fail even if we
    were to review de novo. “A showing of constitu-
    tional error under the Sixth Amendment only merits
    grant of the petition for habeas corpus if the error
    was not harmless, that is, if it had a ‘substantial and
    injurious effect or influence in determining the jury’s
    verdict.’ ” Holley, 568 F.3d at 1100 (quoting Brecht
    v. Abrahamson, 507 U.S. 619, 638 (1993)). Here, as
    the trial judge noted, Petitioner had sufficient alter-
    native avenues for casting doubt on R.H.’s reliabil-
    ity. Further, significant additional evidence linked
    Petitioner to the murder, such that the exclusion of
    one potentially false accusation by R.H. was harm-
    less.

   With this amendment, the panel has voted to deny the peti-
tion for panel rehearing. Judges O’Scannlain and Graber have
voted to deny the petition for rehearing en banc, and Judge
Schroeder has so recommended.

  The full court has been advised of the petition for rehearing
en banc, and no judge of the court has requested a vote on it.

  The petition for panel rehearing and petition for rehearing
en banc are DENIED. No further petitions for panel rehearing
or for rehearing en banc will be entertained.
10260          FENENBOCK v. DIRECTOR OF CORRECTIONS
                               OPINION

GRABER, Circuit Judge:

   Petitioner Robert Morris Fenenbock appeals the district
court’s denial of his petition for habeas corpus, brought under
28 U.S.C. § 2254. His grounds for appeal all pertain to the
prosecution’s primary witness, a minor named R.H. Petitioner
argues that the trial court violated his rights when it denied
him pretrial access to R.H. and then limited cross-examination
of R.H. during the trial. We hold that (1) Petitioner had no
absolute right to pretrial access to R.H, (2) no prosecutorial
interference arose when an unrelated government agency
acted in R.H.’s best interests, and (3) the trial court’s limita-
tions on the length and content of cross-examination were per-
missible.1 Accordingly, we affirm.

         FACTUAL AND PROCEDURAL HISTORY

  During the autumn of 1991 in Hawkins Bar, California,
Petitioner was involved in a series of events leading to the
death of Gary “Hop” Summar.2 Petitioner and seven other
individuals were charged with various crimes related to Sum-
mar’s death. A jury convicted Petitioner of first-degree mur-
der, for which he received a prison term of 25 years to life,
plus one year for use of a deadly weapon.
  1
     There being no error, we need not reach the claim of cumulative error.
See Hayes v. Ayers, 632 F.3d 500, 524 (9th Cir. 2011) (“Because we con-
clude that no error of constitutional magnitude occurred, no cumulative
prejudice is possible.”).
   2
     A full recitation of the facts is found in People v. Fenenbock, 54 Cal.
Rptr. 2d 608, 610-16 (Ct. App. 1996). The federal district court adopted
the state court’s factual summary, verbatim. In adopting the factual sum-
mary, the district court noted that the facts had not been rebutted with
clear and convincing evidence and were therefore presumed correct under
28 U.S.C. § 2254(e)(1) and Davis v. Woodford, 384 F.3d 628, 638 (9th
Cir. 2004). Petitioner does not challenge any of the factual findings on
appeal, so we likewise presume them to be correct.
             FENENBOCK v. DIRECTOR OF CORRECTIONS          10261
  Leading up to the trials, R.H. emerged as a witness. The
day after the murder, Child Protective Services (“CPS”) took
R.H. and his siblings into state custody because of neglect and
potential abuse. Soon thereafter, with the acquiescence of
CPS personnel, law enforcement authorities interviewed R.H.,
and it became clear that he had witnessed Summar’s murder.

   During the trial, the prosecution called R.H. as a witness.
Petitioner’s lawyers sought to speak informally with R.H.
before cross-examination. Essentially, defense counsel were
concerned that the prosecution had obtained substantial pre-
trial access to R.H. and that his therapists and the prosecution
had been coaching him. Richard Bay, R.H.’s court-appointed
lawyer, refused the request to speak with R.H., voicing con-
cern that if he granted pretrial access to counsel for one defen-
dant, he would have to grant access to counsel for each of the
other seven defendants as well. Relying on the advice of
R.H.’s therapists and guardian ad litem, Bay argued that
R.H.’s interests would not be well served by making him
relive the traumatic event over and over again.

   The trial judge held a hearing to address concerns about the
prosecution’s substantial and unilateral pretrial access, as well
as allegations of witness coaching. For example, social work-
ers had prepared R.H. for his testimony by telling him that the
defense lawyers were “crabby” and that “the most important
thing” was to make sure that the defendants stayed in jail.
During that hearing, other troubling facts about R.H.’s prepa-
ration emerged. At one point, a therapist described the prose-
cution as representing R.H.’s interests and stated that defense
counsel would try to “trick” him. The most egregious coach-
ing, including the specific events detailed in this paragraph,
was conducted by private therapists who did not work for the
government.

  Following the hearing, the trial judge determined that
“ample evidence” supported Bay’s decision to refuse pretrial
access to R.H.; accordingly, the trial judge allowed direct and
10262        FENENBOCK v. DIRECTOR OF CORRECTIONS
cross-examination to continue. Later, he held further hearings
and expressly found that the prosecution had played no part
in Bay’s decision.

   In cross-examining R.H., the defense lawyers attacked his
reliability as a witness. As the district court noted in the deci-
sion under review, “during his entire cross-examination, R.H.
frequently answered ‘I don’t remember,’ ‘I don’t know,’ or
‘All I remember is . . . .’ ” For instance, at one point, R.H.
said: “All I remember is . . . dropping off either [Petitioner]
or [one of Petitioner’s co-defendants]. I think we dropped him
off.” R.H. admitted having initially lied to the police about (1)
whether he had seen anyone stab Summar and (2) whether he
previously had been to the location where Summar was killed.
Cross-examination also revealed that R.H. had initially told
his therapists that he had not witnessed any part of the mur-
der.

   During cross-examination, the trial judge noted that R.H.
was showing signs of fatigue, after having sat for about one-
and-a-half hours of direct examination and about two-and-a-
half hours of cross-examination, with a break during cross-
examination. Petitioner’s counsel stated that he wanted “a
couple of days” of cross-examination, but the trial judge lim-
ited him to an additional half day. Defense counsel then com-
pleted his cross-examination with at least four hours to spare.

   The trial judge also limited cross-examination of R.H. with
respect to his allegedly false report, made closer in time to the
trial than to the murder, that his foster father had threatened
his foster mother with a firearm. The judge determined that
the topic was collateral and that it would take too long to liti-
gate the truth of the report, requiring testimony from social
workers, R.H., and R.H.’s foster parents. The trial judge noted
that this topic not only would be too time-consuming but also
               FENENBOCK v. DIRECTOR OF CORRECTIONS                 10263
would not be especially probative given the several other
inconsistencies in R.H.’s testimony.3

   Petitioner appealed his conviction and lost, in what would
be the last reasoned opinion in his case. People v. Fenenbock,
54 Cal. Rptr. 2d 608 (Ct. App. 1996).4 The Supreme Court of
California summarily denied his petition for review. People v.
Fenenbock, No. S055264, 1996 Cal. LEXIS 5688 (Cal. Oct.
2, 1996). Petitioner then filed a habeas petition in federal
court, but the court stayed that petition and held it in abeyance
pending exhaustion of his state claims. Petitioner filed a state
habeas petition that included the arguments presented in this
appeal; the Supreme Court of California summarily denied
that petition as well. In re Fenenbock, No. S102760, 2003
Cal. LEXIS 4251 (Cal. June 25, 2003). Soon thereafter, the
district court lifted the stay on the federal habeas petition,
which proceeded in due course until the district court denied
it and issued a certificate of appealability on the claims in this
appeal. Petitioner timely appeals.

      JURISDICTION AND STANDARDS OF REVIEW

   We have jurisdiction over this appeal pursuant to 28 U.S.C.
§ 2253. We review de novo a district court’s denial of habeas
corpus relief. Robinson v. Ignacio, 360 F.3d 1044, 1055 (9th
Cir. 2004).
  3
    The specific ground for exclusion was California Evidence Code sec-
tion 352, which states:
         The court in its discretion may exclude evidence if its proba-
      tive value is substantially outweighed by the probability that its
      admission will (a) necessitate undue consumption of time or (b)
      create substantial danger of undue prejudice, of confusing the
      issues, or of misleading the jury.
   4
     The discussion of the claims in this case is not contained in the pub-
lished decision; the California appellate court resolved those claims in an
unpublished decision.
10264        FENENBOCK v. DIRECTOR OF CORRECTIONS
   Our review of the underlying state court decisions, on the
other hand, is more limited. Because Petitioner filed his
§ 2254 habeas petition after April 24, 1996, his petition is
governed by the Antiterrorism and Effective Death Penalty
Act (AEDPA) of 1996, Pub. L. No. 104-132, 110 Stat. 1214.
Lambert v. Blodgett, 393 F.3d 943, 965 (9th Cir. 2004). Under
AEDPA, we must defer to a state court’s decision with
respect to any claim that was adjudicated on the merits unless
the adjudication of the claim:

       (1) resulted in a decision that was contrary to, or
    involved an unreasonable application of, clearly
    established Federal law, as determined by the
    Supreme Court of the United States; or

       (2) resulted in a decision that was based on an
    unreasonable determination of the facts in light of
    the evidence presented in the State court proceeding.

28 U.S.C. § 2254(d).

    [A] state has “adjudicated” a petitioner’s constitu-
    tional claim “on the merits” for purposes of
    § 2254(d) when it has decided the petitioner’s right
    to post conviction relief on the basis of the substance
    of the constitutional claim advanced, rather than
    denying the claim on the basis of a procedural or
    other rule precluding state court review of the merits.

Lambert, 393 F.3d at 969.

   Under § 2254(d)(1), a decision involves an “unreasonable
application” of clearly established federal law if it “identifies
the correct governing legal principle from [the Supreme
Court’s] decisions but unreasonably applies that principle to
the facts of the prisoner’s case.” Holland v. Jackson, 542 U.S.
649, 652 (2004) (internal quotation marks omitted).
               FENENBOCK v. DIRECTOR OF CORRECTIONS                   10265
                             DISCUSSION

  A.     Pretrial Access

   [1] The scope of Petitioner’s right to interview R.H. before
trial5 was as follows:
  5
    Petitioner cites no Supreme Court precedent explicitly recognizing the
right to have access to adverse witnesses before trial, but we assume, with-
out deciding, that such a right is necessarily implied by the right to a
“meaningful opportunity to present a complete defense.” Holmes v. South
Carolina, 547 U.S. 319, 324 (2006) (internal quotation marks omitted);
see id. (“Whether rooted directly in the Due Process Clause of the Four-
teenth Amendment or in the Compulsory Process or Confrontation
Clauses of the Sixth Amendment, the Constitution guarantees criminal
defendants a meaningful opportunity to present a complete defense.”
(internal quotation marks omitted)); see also United States v. Valenzuela-
Bernal, 458 U.S. 858, 872 (1982) (discussing when deportation of a wit-
ness might rise to the level of a due process violation); Dennis v. United
States, 384 U.S. 855, 873 (1966) (stating, with respect to grand jury testi-
mony, that “[i]n our adversary system for determining guilt or innocence,
it is rarely justifiable for the prosecution to have exclusive access to a
storehouse of relevant fact,” and that “[e]xceptions to this are justifiable
only by the clearest and most compelling considerations”). We assess this
“right of access” under principles of the Due Process Clause. See Gregory
v. United States, 369 F.2d 185, 188 (D.C. Cir. 1966) (stating that “elemen-
tal fairness and due process require[ ]” that both parties have an equal
opportunity to interview witnesses).
   To the extent that Petitioner seeks to invoke the Confrontation Clause,
his claim fails under the AEDPA standard of review because no clearly
established Supreme Court precedent supports that argument, which
remains subject to dispute. At least one Supreme Court opinion failed to
obtain majority support for the proposition that the Confrontation Clause
is a “trial right” and not “a constitutionally compelled rule of pretrial dis-
covery.” Pennsylvania v. Ritchie, 480 U.S. 39, 52 (1987) (plurality opin-
ion); accord Coleman v. Calderon, 150 F.3d 1105, 1112 (9th Cir.),
reversed on other grounds, 525 U.S. 141, 145 (1998) (per curiam). But see
Kentucky v. Stincer, 482 U.S. 730, 738 n.9 (1987) (“The personal view of
the author [Blackmun, J.] of this opinion as to the Confrontation Clause
is somewhat broader than that of the Ritchie plurality.”); United States v.
Collins, 551 F.3d 914, 925-26 (9th Cir. 2009) (expressing doubt as to Rit-
chie’s scope).
10266          FENENBOCK v. DIRECTOR OF CORRECTIONS
      [A] defendant’s right of access to a witness exists
      co-equally with the witness[’s] right to refuse to say
      anything. The defendant’s right of access is not vio-
      lated when a witness chooses voluntarily not to be
      interviewed. . . . [T]he prosecution may not interfere
      with a witness’s free choice to speak with the
      defense . . . .

United States v. Black, 767 F.2d 1334, 1338 (9th Cir. 1985)
(internal quotation marks and citations omitted); accord
Cacoperdo v. Demosthenes, 37 F.3d 504, 509 (9th Cir. 1994)
(“[The witness] had a right not to be interviewed if she so
chose.”). Thus, a witness’ right to refuse pretrial access is
well established,6 but it is equally well established that the
prosecution may not interfere with a witness’ decision to
grant or refuse pretrial access.7

  Here, Petitioner’s lack of access to R.H. arose from that
witness’ own decision (through his guardian ad litem, his
  6
     “Ninth Circuit caselaw . . . may be persuasive authority for purposes
of determining whether a particular state court decision is an ‘unreason-
able application’ of Supreme Court law, and also may help us determine
what law is ‘clearly established.’ ” Duhaime v. DuCharme, 200 F.3d 597,
600 (9th Cir. 2000).
   7
     See, e.g., Callahan v. United States, 371 F.2d 658, 660 (9th Cir. 1967)
(involving allegations that the United States Attorney’s office or the office
of the United States Marshal had “advised the witnesses not to talk to
defense counsel”); United States v. Gonzales, 164 F.3d 1285, 1288 (10th
Cir. 1999) (involving an Assistant United States Attorney who “instructed
[the witness] to call the defense attorney . . . and tell him she did not want
to talk to defense representatives” and also “threatened defense team
members with prosecution if they continued to ‘harass’ government wit-
nesses”); United States v. Long, 449 F.2d 288, 295-96 (8th Cir. 1971)
(declining to find error where a witness did not want to talk to defense
counsel, and there was “no evidence that his reluctance to talk to the
defendants’ attorneys resulted from any interference by the Government
or its attorneys”); Gregory, 369 F.2d at 187 (involving a prosecutor who
“advis[ed] the witnesses . . . not to speak to anyone unless he were pres-
ent”).
               FENENBOCK v. DIRECTOR OF CORRECTIONS                  10267
appointed counsel, and his social workers) to refuse to be
interviewed by defense counsel. As the district court stated,
“[t]his is no different from a concerned parent refusing to
allow a child to be interviewed by defense counsel.”8

   [2] It is significant, then, that Petitioner can point to no
prosecutorial interference with access to R.H. Instead, Peti-
tioner alleges indirect interference, by means of another arm
of government—CPS, which employed one of the social
workers who worked with R.H. But that argument ignores the
trial court’s express finding that the prosecution did not inter-
fere, even indirectly, with R.H.’s decision. In a habeas case
such as this one, we must defer to that finding unless Peti-
tioner overcomes it with clear and convincing evidence to the
contrary, or at least demonstrates that the finding was an
unreasonable determination of the facts. See 28 U.S.C.
§ 2254(d)(2), (e)(1).

   [3] Accordingly, Petitioner’s denial of access claim fails
for two reasons. First, the record supports the finding that an
interview with defense counsel would have run counter to
R.H.’s best interests. Second, the decisions that Petitioner
faults were made by CPS, not the prosecution. Petitioner can-
not demonstrate prosecutorial interference by pointing to the
independent conduct of a state social services agency that was
acting in loco parentis. Although in some contexts the prose-
cutor may be responsible for what happens in a different gov-
ernment office, see United States v. Blanco, 392 F.3d 382,
394 (9th Cir. 2004) (holding that the government’s obligation
  8
    Citing People v. Pitts, 273 Cal. Rptr. 757, 872-73 (Ct. App. 1990),
Petitioner also argues that California law gives courts discretion to reject
a guardian’s decisions in a criminal case if those decisions would deprive
a defendant of constitutional rights. Even assuming that Petitioner is cor-
rect, and further assuming that, as Petitioner argues, the trial judge misap-
prehended his role in this regard, Petitioner still cannot demonstrate that
such a mistake would be “contrary to, or involved an unreasonable appli-
cation of, clearly established Federal law, as determined by the Supreme
Court of the United States.” 28 U.S.C. § 2254(d)(1) (emphasis added).
10268          FENENBOCK v. DIRECTOR OF CORRECTIONS
to disclose exculpatory evidence under Brady v. Maryland,
373 U.S. 83 (1963), and Giglio v. United States, 405 U.S. 150
(1972), applies “not only [to] the prosecutor, but [to] the gov-
ernment as a whole”), here we must respect the separate
authority of a state agency charged with protecting the inter-
ests of children, see Maryland v. Craig, 497 U.S. 836, 853
(1990) (“[A] State’s interest in the physical and psychological
well-being of child abuse victims may be sufficiently impor-
tant to outweigh, at least in some cases, a defendant’s right to
face his or her accusers in court.”). If a state’s interest in pro-
tecting the interests of children can, in some circumstances,
permit trial testimony by one-way closed-circuit television,
id., then those interests also can support the denial of pretrial
access to a witness who has an indisputable right to refuse
such access. See United States v. Rouse, 111 F.3d 561, 566
(8th Cir. 1997) (“When a child witness is in the legal custody
of a social services agency, that agency as custodian may
refuse requests for pretrial interviews.”).9

  [4] Petitioner did not raise the denial-of-access claim until
he filed his state habeas petition, so the last reasoned opinion,
  9
    Petitioner cites cases holding that a due process violation arises when
the government deports a potentially favorable witness, thereby denying
access to that witness. See, e.g., United States v. Mendez-Rodriguez, 450
F.2d 1, 4 (9th Cir. 1971), overruled by United States v. Valenzuela-Bernal,
458 U.S. 858 (1982), as stated in United States v. Medina-Villa, 567 F.3d
507, 516 (9th Cir. 2009). But intervening Supreme Court rulings have sig-
nificantly narrowed that rule to require a showing “that the Government
acted in bad faith and that this conduct resulted in prejudice to the defen-
dant’s case.” Medina-Villa, 567 F.3d at 517 (internal quotation marks
omitted). Bad faith is relevant to the inquiry in such cases because the
denial of access relates to potentially exculpatory evidence, rather than
evidence known to be exculpatory. United States v. Dring, 930 F.2d 687,
693 n.7 (9th Cir. 1991). This case, similarly, involves denial of access to
potentially exculpatory evidence—the possibility that R.H. would have
told a different version of his story. Thus, even if we were to apply the
reasoning of the deportation cases, Petitioner could not prevail without
showing prosecutorial bad faith, which he has failed to do. See Medina-
Villa, 567 F.3d at 517.
             FENENBOCK v. DIRECTOR OF CORRECTIONS          10269
which the California appellate court issued in his direct
appeal, contains no discussion of the matter. See Robinson,
360 F.3d at 1055 (noting that we review the “last reasoned
decision” of a state court addressing the issue at hand). The
state supreme court denied the state habeas petition without
explanation. We must therefore “independently review the
record, [but] we still defer to the state court’s ultimate deci-
sion.” Pirtle v. Morgan, 313 F.3d 1160, 1167 (9th Cir. 2002);
see also Harrington v. Richter, 131 S. Ct. 770, 784 (2011)
(“Where a state court’s decision is unaccompanied by an
explanation, the habeas petitioner’s burden still must be met
by showing there was no reasonable basis for the state court
to deny relief.”). That is, although we must decide indepen-
dently whether the state court could have reached its conclu-
sion without applying clearly established federal law
improperly, AEDPA still operates to limit the governing law
to Supreme Court precedents. Petitioner has failed to identify
any such precedent to support the contention that he suffered
a violation of his right to pretrial access to R.H., and we have
discovered none. Accordingly, we find no error.

  B.   Time Limit on Cross-Examination

   [5] Petitioner argues that the time limit on his cross-
examination of R.H. amounted to a violation of the Confron-
tation Clause of the Sixth Amendment. The “main and essen-
tial purpose of confrontation is to secure for the opponent the
opportunity of cross-examination.” Delaware v. Van Arsdall,
475 U.S. 673, 678 (1986) (internal quotation marks omitted).
“Cross-examination is the principal means by which the
believability of a witness and the truth of his testimony are
tested[, allowing the cross-examiner] . . . to delve into the wit-
ness’ story to test the witness’ perceptions and memory . . .
[and] to impeach, i.e., discredit, the witness.” Davis v. Alaska,
415 U.S. 308, 316 (1974).

   [6] But the Supreme Court has repeatedly emphasized that
the right is limited to the guarantee of “an opportunity for
10270       FENENBOCK v. DIRECTOR OF CORRECTIONS
effective cross-examination, not cross-examination that is
effective in whatever way, and to whatever extent, the defense
might wish.” Van Arsdall, 475 U.S. at 679 (internal quotation
marks omitted). Accordingly, “trial judges retain wide latitude
insofar as the Confrontation Clause is concerned to impose
reasonable limits on such cross-examination based on con-
cerns about, among other things, harassment, prejudice, con-
fusion of the issues, the witness’ safety, or interrogation that
is repetitive or only marginally relevant.” Id. (emphases
added).

  [7] Generally speaking, a court violates the Confrontation
Clause only when it prevents a defendant from examining a
particular and relevant topic, such as bias:

    The Supreme Court consistently has held that a Con-
    frontation Clause violation occurs when a trial judge
    prohibits any inquiry into why a witness may be
    biased. However, when some inquiry is permitted,
    trial judges retain wide latitude to impose reasonable
    limits on such cross-examination. No Confrontation
    Clause violation occurs as long as the jury receives
    sufficient information to appraise the biases and
    motivations of the witness.

Hayes v. Ayers, 632 F.3d 500, 518 (9th Cir. 2011) (internal
quotation marks, citations, and ellipsis omitted); see also
Olden v. Kentucky, 488 U.S. 227, 231 (1988) (per curiam).
For example, in Van Arsdall, the Court found a Confrontation
Clause violation because the court had “cut[ ] off all question-
ing about an event that the State conceded had taken place
and that a jury might reasonably have found furnished the wit-
ness a motive for favoring the prosecution in his testimony.”
475 U.S. at 679. Similarly, in Davis, an error arose when the
trial court granted a protective order prohibiting the defense
from introducing a witness’ juvenile adjudication, not even
for the purpose of demonstrating that the witness “might have
               FENENBOCK v. DIRECTOR OF CORRECTIONS                  10271
been subject to undue pressure from the police” or “under fear
of possible probation revocation.” 415 U.S. at 311.

   [8] Indeed, a limitation on cross-examination that excludes
testimony on a particular topic might violate the rule that
“[r]estrictions on a criminal defendant’s rights to confront
adverse witnesses and to present evidence may not be arbi-
trary or disproportionate to the purposes they are designed to
serve.” Michigan v. Lucas, 500 U.S. 145, 151 (1991) (internal
quotation marks omitted); see also Holley v. Yarborough, 568
F.3d 1091, 1099 (9th Cir. 2009). For that reason, limiting the
time allotted to cross-examination is often considered a better
approach than limiting the subject matter. See Holley, 568
F.3d at 1100 (“[T]he court could have limited the time allot-
ted to discussion of the [objectionable topic], rather than
excluding all discussion.”).

   [9] Here, the trial court adopted that preferred approach by
limiting the time allotted for cross-examination. Petitioner
presents no cogent explanation as to why the time used by his
defense counsel at trial (about three hours) plus the unused
four hours offered by the trial court would not have sufficed
to explore the intended material exhaustively. All he can point
to is defense counsel’s unexplained assertion to the trial court
that he needed two days to cover four hundred pages of dis-
covery. In this circumstance, the limit was reasonable and did
not run afoul of any of the Supreme Court’s Confrontation
Clause precedents.10
  10
     Our conclusion is unaffected by the trial judge’s apparent motivation
for imposing a time limit—R.H.’s discomfort or anxiety. Davis is not to
the contrary. That decision held that, when a juvenile witness might suffer
“temporary embarrassment” because of inquiry into a particular topic of
cross-examination, that embarrassment can be “outweighed by [a defen-
dant]’s right to probe” that topic. 415 U.S. at 319. Davis simply reiterates
the rule that restrictions on the content of cross-examination are subject to
more searching review; it says nothing about restrictions on the duration
of cross-examination.
10272          FENENBOCK v. DIRECTOR OF CORRECTIONS
   Petitioner’s argument would fail even under de novo
review. It therefore also fails under the more stringent
AEDPA standard of review that applies here, where the state
appeals court properly identified and applied the relevant
rules in adjudicating this claim on the merits. See Frantz v.
Hazey, 533 F.3d 724, 737 (9th Cir. 2008) (en banc) (holding
that a court may “decide the § 2254(d)(1) issue . . . by decid-
ing the constitutional issue de novo first”).

  C.    Limit on Collateral Impeachment

  [10] The trial judge did preclude cross-examination of one
particular topic—R.H.’s out-of-court allegations about his
foster father’s threat to his foster mother and about the truth
of that accusation. The trial judge reasoned that injecting the
topic would confuse the issues and consume undue time. In
addition, the judge observed that, even if R.H. were
impeached, the benefit to Petitioner would be only marginal
because of other significant areas of impeachment.

   [11] The trial judge acted within his discretion, citing con-
cerns repeatedly recognized as valid by the Supreme Court.
See Van Arsdall, 475 U.S. at 679 (recognizing concerns such
as “confusion of the issues . . . or interrogation that is repeti-
tive or only marginally relevant”). Petitioner cites no Supreme
Court opinion recognizing a right to impeachment via extrin-
sic evidence relating to the truth of a collateral out-of-court state-
ment.11 “When there is no clearly established federal law on
an issue, a state court cannot be said to have unreasonably
  11
     The relevant Supreme Court cases are more concerned with a witness’
motive to lie. For example, Olden involved an attempt to cross-examine
a witness as to whether or not she was involved in a relationship with and
living with a man, after she had testified during direct examination that
she was living with her mother; the fact of her cohabitation was relevant
in that it suggested a motive to lie. 488 U.S. at 230. In Van Arsdall, the
excluded topic of cross-examination concerned whether the prosecution
had agreed to drop certain charges against a witness in exchange for his
promise to discuss the murder in which the defendant was charged. 475
U.S. at 676. Similarly, Davis involved cross-examination relating to a wit-
ness’ probationary status, intended to show that he might have testified
due to undue pressure from police or fear of probation revocation. 415
U.S. at 311. None of these cases involved cross-examination about the
truth or falsity of an out-of-court statement relating to a collateral matter.
               FENENBOCK v. DIRECTOR OF CORRECTIONS                   10273
applied the law as to that issue.” Holley, 568 F.3d at 1098.
Thus, under the usual AEDPA standard of review, this claim
fails.12

   AFFIRMED.




  12
     In briefing and at oral argument, the parties agreed that the last rea-
soned state court opinion addressed the constitutional question. In our
view, that opinion resolved Petitioner’s claim on only state evidentiary
grounds. See Williams v. Cavazos, 646 F.3d 626, 636-37 (9th Cir. 2011),
cert. granted, 132 S. Ct. 1088 (2012). But it is possible that the state
supreme court later implicitly ruled on the constitutional claim, albeit
without explanation, when it decided Petitioner’s habeas claims. See Rich-
ter, 131 S. Ct. at 784; see also Williams, 646 F.3d at 636.
   Regardless, we need not resolve the question because Petitioner’s
claims would fail even if we were to review de novo. “A showing of con-
stitutional error under the Sixth Amendment only merits grant of the peti-
tion for habeas corpus if the error was not harmless, that is, if it had a
‘substantial and injurious effect or influence in determining the jury’s ver-
dict.’ ” Holley, 568 F.3d at 1100 (quoting Brecht v. Abrahamson, 507 U.S.
619, 638 (1993)). Here, as the trial judge noted, Petitioner had sufficient
alternative avenues for casting doubt on R.H.’s reliability. Further, signifi-
cant additional evidence linked Petitioner to the murder, such that the
exclusion of one potentially false accusation by R.H. was harmless.
