with whom Justice Marshall and Justice Stevens join, dissenting.
The Court holds today that an order of a federal habeas court requiring release or retrial of a state prisoner because of constitutional violations at bis trial must be vacated if the *553court does not explain in its order why 28 U. S. C. § 2254 (d) does not bar re-examination of issues decided by the state courts — even if the State did not contest the order on the ground of § 2254 (d), and even if § 2254 (d) is plainly inapplicable under decisions of this Court. I dissent.
I
Respondent was convicted of first-degree murder of another prisoner, largely on the strength of identification testimony by three fellow inmates at a California penitentiary. Two of these witnesses had been shown photo identification arrays on three occasions, under circumstances that led the United States Court of Appeals for the Ninth Circuit to conclude that it was “obvious that there was a grave likelihood of irreparable misidentification.” 611 F. 2d 754, 758 (1979). Respondent did not object at trial to admission of this identification testimony. On appeal to the California Court of Appeal, respondent argued that the use of this identification evidence violated his due process rights as defined in Simmons v. United States, 390 U. S. 377 (1968). The court considered this claim on the merits, and rejected it.
Respondent did not seek review in the California Supreme Court. Instead, he raised the pretrial identification issue in state habeas corpus proceedings, where his petitions were denied without opinion. Finally, he filed a petition for habeas corpus under 28 U. S. C. § 2254 in the United States District Court for the Northern District of California, again raising the pretrial identification issue. In his return in opposition to respondent’s petition for habeas corpus, petitioner argued that the District Court was precluded from re-examining the issue by virtue of § 2254 (d), which accords a presumption of correctness to state-court factual findings, subject to certain exceptions not relevant here.1 The District Court denied the petition on its merits, without referring to *554§ 2254 (d). Respondent appealed to the Court of Appeals for the Ninth Circuit, where petitioner abandoned his § 2254 (d) argument. That court reversed on the merits, finding that respondent’s due. process rights had been violated by the pretrial identification procedures. It did not refer to § 2254 (d). Petitioner then filed a motion for rehearing and suggestion for rehearing en banc, this time including a one-sentence argument that § 2254 (d) barred the federal court from reaching the pretrial identification issue. The Court of Appeals denied these motions without discussion.
II
I cannot join my Brethren in concluding that the Court of Appeals’ decision must be vacated for its failure to discuss an issue not timely raised by petitioner. This Court today holds that a federal habeas court may not grant a petition for a writ without stating on the record why it was not bound by § 2254 (d) to defer to the state-court judgment. Ante, at 551. It therefore vacates the judgment of the Court of Appeals in this case, even though petitioner failed to raise the § 2254 (d) argument in his briefs before that court. The Court admits that “a court need not elaborate or give reasons for rejecting claims which it regards as frivolous or totally without merit.” Ante, at 548. To that I would add that, except in exceptional circumstances, a court need not search the universe of legal argument and discuss every contention that might have been — but was not — made by the losing party. The burden on the dockets of the federal courts is severe enough already, without requiring the courts to raise, research, and explain an issue not deemed important enough by the parties to justify mention in their briefs.
Moreover, I cannot agree that today’s holding will “ensure that this mandate of Congress [§ 2254 (d)] is enforced,” ante, at 551; rather, it is more likely to be seen as an invitation to lower federal courts to “inser [t] a boilerplate paragraph” in their opinions acknowledging their awareness of § 2254 (d). *555See ante, at 549.2 The requirement is as useless as it is disruptive.
Ill
The Court’s disposition of the instant case is all the more perplexing because § 2254 (d) plainly constitutes no bar to the Court of Appeals’ holding that the pretrial identification procedure employed by the police violated respondent’s due process rights. Section 2254 (d) requires a federal habeas court to defer to “a determination after a hearing on the merits of a factual issue, made by a State court . . . .” 28 U. S. C. § 2254 (d) (emphasis supplied). The factual issues to which § 2254 (d) applies are “basic, primary, or historical facts: facts 'in the sense of a recital of external events and the credibility of their narrators. . . .’” Cuyler v. Sullivan, 446 U. S. 335, 342 (1980) (quoting Townsend v. Sain, 372 U. S. 293, 309, n. 6 (1963)). Section 2254 (d) does not bar a federal court from reviewing “a mixed determination of law and fact that requires the application of legal principles to the historical facts of this case.” 446 U. S., at 342; see Brewer v. Williams, 430 U. S. 387, 403-404 (1977).
*556What factual determinations did the Court of Appeals for the Ninth Circuit disregard? The court did not conduct an evidentiary hearing on the pretrial identification procedures, but relied on the same state trial court record relied upon by the California Court of Appeal. My examination of the opinions of the two courts does not reveal a single disagreement over a “basic, primary, or historical fact.”
The treatment of the pretrial identification issue by the California court was brief and contained little in the way of formal factual findings. Its relevant findings were that “the witnesses had an adequate opportunity to view the crime”; that “there is no showing of influence by the investigating officers”; and that the witnesses’ “descriptions are accurate.” App. to Pet. for Cert. C-4 to C-5. The Court of Appeals for the Ninth Circuit explicitly agreed that the witnesses had “an opportunity ... to observe the perpetrators of the crime,” 611 F. 2d, at 758, but disagreed with the California court’s legal conclusion that the opportunity for observation was constitutionally adequate, because of the “diversion of the witnesses’ attention at the time the crime was committed.” Id., at 759. Similarly, the Court of Appeals’ description of the facts concerning the photographic lineup procedure differs in no significant detail from that offered by the California court. Compare id., at 756, with App. to Pet. for Cert. C-3 to C-4. The California court, however, concluded that “[t]he circumstances thus indicate the inherent fairness of the procedure,” id., at C-5, while the Court of Appeals reached the opposite legal conclusion. The Court of Appeals, like the California court, did not dispute the accuracy of the witnesses’ identifications, but only their degree of detail. 611 F. 2d, at 758. Finally the Court of Appeals considered whether using a photo array procedure rather than a lineup was necessary, a consideration not deemed relevant by the California court. Id., at 757.
Plainly, the disagreement between the courts is over the constitutional significance of the facts of the case, and not *557over the facts themselves. Whether a witness’ opportunity to view a crime is “adequate” for constitutional purposes, whether a particular course of conduct by state police raises a possibility of irreparable misidentification serious enough to violate constitutional standards, whether a witness’ description is sufficiently detailed to dispel doubt about the procedures imposed, and whether the necessity for a photographic identification procedure is constitutionally significant are examples of questions of law, or at least mixed questions of fact and law. The questions addressed by the Court of Appeals for the Ninth Circuit required the “ 'application of constitutional principles to the facts as found,’ ” Brewer v. Williams, supra, at 403 (quoting Brown v. Allen, 344 U. S. 443, 507 (1953) (opinion of Frankfurter, J.)), and thus fall outside the limitations of § 2254 (d).
Indeed, this Court has held, in a case similar on its facts to this one, that a dispute over allegedly suggestive pretrial identification procedures is “not so much over the elemental facts as over the constitutional significance to be attached to them.” Neil v. Biggers, 409 U. S. 188, 193, n. 3 (1972). Cf. Cuyler v. Sullivan, supra, at 342 (conclusion that lawyers undertook multiple representation not a “factual” determination within the meaning of § 2254 (d)); Brewer v. Williams, supra, at 395-397, 402-404 (conclusion that defendant waived his right to counsel not a “factual” determination within the meaning of § 2254 (d)).
In Biggers, the District Court and the Court of Appeals for the Sixth Circuit, applying the “totality of the circumstances” test of Simmons v. United States, 390 U. S. 377 (1968), both concluded that pretrial identification procedures had violated a state prisoner’s due process rights. This Court reversed, over a dissent claiming that the Court was violating its “long-established practice not to reverse findings of fact concurred in by two lower courts unless shown to be clearly erroneous.” Neil v. Biggers, supra, at 202 (Brennan, J., joined by Douglas and Stewart, JJ., dissenting). *558The Court rejected the dissenters’ argument on the basis of its conclusion that application of the “totality of the circumstances” test to the undisputed primary facts in the trial court record did not constitute a factual finding. 409 U. S., at 193, n. 3. The instant case is indistinguishable. It is cruelly ironic that the Court would hold the constitutionality of pretrial identification procedures to be a question of law when the effect is to vacate a decision in favor of a prisoner whose incarceration had been held unconstitutional by lower courts, but would reject the same conclusion when the effect would be to vindicate such a prisoner’s constitutional rights.
On the merits, petitioner contends that the “Ninth Circuit’s application of an erroneous standard led it to an erroneous result and that application of the proper standard must lead to a conclusion that [respondent] was not denied due process by reason of the admission of identification evidence at his trial.” Brief for Petitioner 49 (emphasis supplied); see also id., at 14.3 Thus, petitioner’s very argument reveals that the difference between the Court of Appeals for the Ninth Circuit and the California Court of Appeal was over the applicable legal standard, and not over the particular facts of the case. And § 2254 (d) surely does not detract from the well-established duty of federal courts “to apply the applicable federal law to the state court fact findings independ*559ently.” Townsend v. Sain, 372 U. S., at 318. A federal court need not — indeed, must not — defer to the state court’s interpretation of federal law. Ibid.; see ante, at 543-544.4 In view of this, I cannot understand how the Court today can conclude that “[i]t is obvious from a literal reading of [§ 2254 (d)] that § 2254 (d) is applicable to the present situation ....” Ante, at 545. To me, it is just as obvious that § 2254 (d) is not applicable.
IV
The Court does not challenge the correctness of the Court of Appeals’ conclusion that the pretrial identification procedure employed by the state police in this case was “so imper-missibly suggestive as to give rise to a very substantial likelihood of irreparable misidentification.” 611 F. 2d, at 759. It is therefore not necessary to review the portions of the record and the precedents of this Court that support the conclusion of the Court of Appeals. Nevertheless, today’s decision denies respondent the relief to which that court found that he is entitled. Since petitioner did not raise the § 2254 (d) issue in the Court of Appeals, and since § 2254 (d) is plainly inapplicable to the mixed question of law and fact at issue in this case, I can see no justice in this result. I therefore respectfully dissent.
See ante, at 544-545.
The Court admits that the decision in Taylor v. Lombard, 606 F. 2d 371 (CA2 1979), cert. denied, 445 U. S. 946 (1980), would be sustained under the rule announced today. Ante, at 547-548. The sole discussion of § 2254 (d) by the Court of Appeals for the Second Circuit in Taylor was its conclusory statement: “The County Court’s finding that there was no factual basis for the claim of perjury is not fairly supported by the record, and therefore is not entitled to deference. 28 U. S. C. § 2254 (d) (8).” 606 F. 2d, at 375. On the basis of this statement, we no more know whether the Court of Appeals for the Second Circuit correctly applied § 2254 (d) in Taylor than we know whether the Court of Appeals for the Ninth Circuit correctly applied it in the instant case. Admittedly, the Second Circuit opinion manifested “full awarenesss” of the existence of §2254 (d), see ante, at 548, but it nevertheless “left [us] to guess as to [its] reasons for granting relief notwithstanding the provisions of §2254 (d).” See ante, at 552. I would be content to presume that federal judges are fully aware of so prominent a statute as §2254 (d), and to leave them free to devote their energies to writing opinions concerning contested issues.
In particular, petitioner argues that the Court of Appeals for the Ninth Circuit’s consideration of the necessity for using pretrial photo displays was in conflict with this Court’s precedents. Brief for Petitioner 31. The Court of Appeals has held that the necessity for the use of a photographic display is an important factor in judging the validity of pretrial identification procedures, though lack of necessity is not a per se ground for rejecting the identification. 611 F. 2d, at 757; see United States v. Calhoun, 542 F. 2d 1094, 1104 (CA9 1976), cert. denied, 429 U. S. 1064 (1977). The California Court of Appeal did not consider the necessity for the use of the photographic displays, and thus did not apply the same legal standard to the pretrial identification question. App. to Pet. for Cert. C-4 to C-5; see People v. Suttle, 90 Cal. App. 3d 572, 580-581, 153 Cal. Rptr. 409, 414-415 (1979).
The Court does not suggest, nor could it, that this case falls within the exception to this general principle enunciated in Stone v. Powell, 428 U. S. 465 (1976).