MEMORANDUM *

*674Joshua Seth Romero appeals from the district court’s denial of his 28 U.S.C. § 2254 petition, challenging his jury-trial conviction for first degree manslaughter and first degree unlawful possession of a firearm. We granted a certificate of ap-pealability as to three ineffective assistance of trial counsel claims. We have jurisdiction pursuant to 28 U.S.C. § 2253. We affirm.

We review de novo the district court’s denial of a habeas corpus petition. Tanner v. McDaniel, 493 F.3d 1135, 1139 (9th Cir. 2007). To obtain habeas relief, Romero must demonstrate that the Washington state court’s decision1 was “contrary to, or involved an unreasonable application of, clearly established Federal law, as determined by the Supreme Court of the United States.” 28 U.S.C. § 2254(d)(1).

Where the state court makes “mistakes in reasoning” or adopts “the wrong legal rule or framework,” however, this court evaluates de novo petitioner’s constitutional claims in an inquiry that is not limited to the reasoning of the state court. Frantz v. Hazey, 513 F.3d 1002, 1012, 1016 (9th Cir. 2008) (en banc). Accordingly, we ask with respect to each of Romero’s claims whether the state court properly applied the prejudice prong from Strickland v. Washington such that our review should be de novo. See 466 U.S. 668, 694, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984) (holding that a petitioner must show “there is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different”); see also Jackson v. Calderon, 211 F.3d 1148, 1155 n. 3 (9th Cir. 2000) (citing Strickland for the proposition that we “need not decide whether counsel’s performance was deficient when the claim of ineffectiveness may be rejected for lack of prejudice”).

With respect to Romero’s claim that his trial counsel’s failure to present a diminished capacity defense constituted ineffective assistance of counsel, the Commissioner correctly applied the standard set forth in Strickland. Romero’s testimony regarding his actions immediately before and after the shooting suggests that he understood that his actions were reckless and that he was concocting an elaborate alibi. Accordingly, habeas corpus relief is not warranted on this claim.

As to Romero’s counsel’s use of an excusable homicide defense, the Commissioner’s decision was “contrary to” Supreme Court precedent because the Commissioner utilized Washington’s “actual and substantial prejudice” standard rather than the standard under Strickland. Frantz, 513 F.3d at 1012; Barker v. Fleming, 423 F.3d 1085, 1095 n. 5 (9th Cir. 2005) (noting the conflict between Washington’s “actual and substantial prejudice” standard and other federal prejudice standards). We apply de novo review, but conclude that Romero cannot demonstrate a reasonable possibility that the outcome of his trial would have been different if counsel had not submitted a jury instruction setting forth the statutory defense of excusable homicide and also stipulated to facts making the defense legally impossible. See Strickland, 466 U.S. at 694, 104 S.Ct. 2052. The evidence against Romero was substantial. Additionally, the excusable homicide jury instruction indicated that excusable homicide was a defense to the charge of second degree murder and both charges of manslaughter. Romero suffered no prejudice because the jury acquit*675ted him of second degree murder, demonstrating that it did not mistakenly believe that it must convict Romero of the most serious charge against him if it rejected the excusable homicide defense.

Likewise, the Commissioner’s decision regarding trial counsel’s failure to interview the state’s expert witness was also “contrary to” Supreme Court precedent because the Commissioner applied an incorrect legal standard. See Frantz, 513 F.3d at 1012; Barker, 423 F.3d at 1095 n. 5. Even applying de novo review, however, Romero cannot show that there is a reasonable probability that the outcome would have been different if trial counsel had interviewed the state’s pathologist pri- or to trial. See Strickland, 466 U.S. at 694, 104 S.Ct. 2052. During his testimony, the state’s pathologist clarified that his characterization of Russian roulette was not a legal definition and might not even extend to other pathologists. Additionally, even assuming that the pathologist’s testimony made the version of events in Romero’s videotaped interview more likely, Romero expressly refuted his videotaped statement at trial. As a result, Romero cannot demonstrate prejudice.

AFFIRMED.