The state cites a number of cases in support of its position that Buckwalter's performance was not deficient under the circumstances. See Burger v. Kemp, 483 U.S. 776, 97 L. Ed. 2d 638, 107 S. Ct. 3114 (1987); Darden v. Wainwright, 477 U.S. 168, 91 L. Ed. 2d 144, 106 S. Ct. 2464 (1986); Babbitt v. Calderon, 151 F.3d 1170 (9th Cir. 1998); Coleman v. Calderon, 150 F.3d 1105 (9th Cir. 1998); Campbell v. Kincheloe, 829 F.2d 1453 (9th Cir. 1987). In all of these cases, the court declined to find ineffective assistance in the context of an attorney's failure to present guilt-or penalty-phase evidence.

Key PrecedentSixth Amendment to the U.S. Constitution (“In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial . . . and to have the assistance of counsel for his defense.”)Strickland v. Washington, 466 U.S. 668 (1984) (to prove a claim of ineffective assistance of counsel, the defendant must show that: (1) counsel’s performance was deficient, and (2) the deficient performance prejudiced the defense.)Burger v. Kemp, 483 U.S. 776 (1987) (the decision by trial counsel to focus solely on the defendant’s positive mitigation evidence was professionally reasonable in order to avoid the jury learning of the defendant’s violent past and disturbed family background.)Williams v. Taylor,529 U.S. 362 (2000) (trial counsel has the duty to conduct a diligent investigation into a client’s background and personal circumstances.)Rompilla v. Beard, 545 U.S. 374 (2005) (trial counsel provided ineffective assistance of counsel by failing to follow several available avenues of investigation that would have led to the discovery of compelling mitigation evidence.)

Although this standard excuses a petitioner from proving prejudice under Strickland, it does not lack teeth.First, the conflict of interest must be active; possible or potential conflicts will not satisfy this requirement. See, e.g., Burger v. Kemp, 483 U.S. 776, 783, 107 S. Ct. 3114, 97 L. Ed. 2d 638 (1987) (holding that possible conflict of interest arising out of attorney's participation in co-defendant's trial "did not so infect [petitioner's] representation as to constitute an active representation of competing interests"); United States v. Burns, 990 F.2d 1426, 1438 (4th Cir. 1993) (finding that defendant's state bar grievance petition against his lawyer did not create an actual conflict because the attorney could not [*14] "have gleaned any advantage for himself in disciplinary proceedings before the state bar by failing to employ his best exertions . . . at trial").Moreover, even if a petitioner can establish the first element -- an actual conflict of interest -- he will not be entitled to the Sullivan prejudice presumption unless he can also demonstrate the second element -- that "the conflict has significantly affeected counsel's performance."

See Williamson v. Ward, 110 F.3d 1508, 1514 (10th Cir. 1997) ("In assessing counsel's conduct, we are mindful of the Supreme Court's observation that 'our duty to search for constitutional error with painstaking care is never more exacting than it is in a capital case.'") (quoting Burger v. Kemp, 483 U.S. 776, 785, 97 L. Ed. 2d 638, 107 S. Ct. 3114 (1987)). Our heightened attention parallels the heightened demands on counsel in a capital case.

We conclude that he has.Reasonable jurists could conclude that the low IQ evidence Tennard presented was relevant mitigating evidence. Evidence of significantly impaired intellectual functioning is obviously evidence that “might serve ‘as a basis for a sentence less than death,’”Skipper, 476 U.S., at 5; see also,e.g.,Wigginsv.Smith,539 U.S. 510, 535 (2003) (observing, with respect to individual with IQ of 79, that “Wiggins[’] … diminished mental capacitie[s] further augment his mitigation case”);Burgerv.Kemp,483 U.S. 776, 779, 789 n.7 (1987) (noting that petitioner “had an IQ of 82 and functioned at the level of a 12-year-old child,” and later that “[i]n light of petitioner’s youth at the time of the offense, … testimony that his ‘mental and emotional development were at a level several years below his chronological age’ could not have been excluded by the state court” (quotingEddings, 455 U.S., at 116)).Reasonable jurists also could conclude that the Texas Court of Criminal Appeals’ application ofPenryto the facts of Tennard’s case was unreasonable.

Requiring the prosecution, on its own, to disclose information that might fit some defense theory but is irrelevant to the prosecution evidence or theory of the case is generally not necessary to ensure a fair trial. Because mitigation is often " ' "in the eye of the beholder" ' " (Burger v. Kemp (1987) 483 U.S. 776, 794 [97 L. Ed. 2d 638, 107 S. Ct. 3114]), the defense will know far better than the prosecution what evidence fits its theory of the case and what evidence does not. Because the defense can offer virtually anything about the defendant personally that it considers mitigating, virtually anything regarding the defendant can be exculpatory if the defense considers it so.

More-over, given the strength of the available evidence, a reasonable attorney may well have chosen to prioritize the mitigation case over the direct responsibility challenge, particularly given that Wiggins’ history contained little of the double edge we have found to justify limited investigations in other cases. Cf. Burger v. Kemp, 483 U.S. 776 (1987); Darden v. Wainwright, 477 U.S. 168 (1986).The dissent nevertheless maintains that Wiggins’ counsel would not have altered their chosen strategy of focusing exclusively on Wiggins’ direct responsibility for the murder.

More over, given the strength of the available evidence, a reasonable attorney may well have chosen to prioritize the mitigation case over the direct responsibility challenge, particularly given that Wiggins’ history contained little of the double edge we have found to justify limited investigations in other cases. Cf. Burger v. Kemp, 483 U.S. 776 (1987); Darden v. Wainwright, 477 U.S. 168 (1986).The dissent nevertheless maintains that Wiggins’ counsel would not have altered their chosen strategy of focusing exclusively on Wiggins’ direct responsibility for the murder.

In Darden v. Wainwright, 477 U.S. 168, 184 (1986), for example, we evaluated under Strickland a claim that counsel was ineffective for failing to put on any mitigating evidence at a capital sentencing hearing. In Burger v. Kemp, 483 U.S. 776, 788 (1987), we did the same when presented with a challenge to counsels decision at a capital sentencing hearing not to offer any mitigating evidence at all.We hold, therefore, that the state court correctly identified the principles announced in Strickland as those governing the analysis of respondents claim. Consequently, we find no merit in respondents contention that the state courts adjudication was contrary to our clearly established law.

How much more effective to have brought out the wrenching abuse she and Karis suffered and then leave the mother crying on the stand. A reasonable investigation and witness preparation would have made this possible.The dissent further contends that the result reached by the majority in this case is precluded by Burger v. Kemp, 483 U.S. 776, 97 L. Ed. 2d 638, 107 S. Ct. 3114 (1987). In that case the attorney made a strategic decision not to call witnesses to testify about his troubled family background because it would inevitably reveal his criminal juvenile background and his hair trigger violent temper, both of which the jury had no knowledge.