Opinion by Judge PAEZ; Dissent by Judge TALLMAN
OPINION
PAEZ, Circuit Judge:
A California jury convicted William Charles Payton (“Payton”) of the first degree murder and rape of Pamela Montgomery and the attempted murder of Patricia Pensinger and her son, Blaine Pensinger. Payton was sentenced to death. Payton appealed both his underlying conviction and death sentence.
On direct appeal, the California Supreme Court affirmed both his conviction and his sentence. People v. Payton, 3 Cal.4th 1050, 13 Cal.Rptr.2d 526, 839 P.2d 1035 (1992). Payton filed a petition for a writ of habeas corpus and a subsequent amended habeas petition in federal district court, pursuant to 28 U.S.C. § 2254, after exhausting his state court remedies.
Payton raised several arguments in his habeas petition relating to the guilt and penalty phases of his trial. At issue here is Payton’s contention that the jury did not consider, in imposing the death penalty, potentially mitigating evidence of his post-crime religious conversion and good behavior in prison. The California death penalty statute contains an eleven-factor test that requires the jury to weigh and balance specific aggravating and mitigating circumstances in deciding whether to impose the death penalty. The first ten factors instruct the judge or jury to evaluate various circumstances specific to the crime and to account for the defendant’s age and prior convictions. The eleventh factor— factor (k) — functions as a catchall factor, [1206]*1206enabling the judge or jury to consider any other circumstance that the defendant presents in mitigation of a death sentence. During Payton’s penalty phase, the trial court used the then-existing model jury instruction that incorporated this multi-factor test. See 1 California Jury Instructions, Criminal (“CALJIC”) 8.84.1 (4th ed.1979). This instruction simply quotes factor (k) as it exists in the death penalty statute, directing the jury to consider any circumstance “which extenuates the gravity of the crime even though it is not a legal excuse for the crime.” Id.; Cal.Penal Code § 190.3 (1978). Payton contended that, although the jury instruction enabled the jury to consider pre-crime character and background evidence, see Boyde v. California, 494 U.S. 370, 110 S.Ct. 1190, 108 L.Ed.2d 316 (1990), it limited the permissible scope of factor (k) in such a way as to remove from the jury’s consideration the only mitigating evidence he presented during the penalty phase of his trial— evidence of his post-crime religious conversion and good behavior in prison.
The district court rejected Payton’s guilt phase arguments but agreed with his penalty phase arguments. The court therefore granted Payton’s habeas petition and vacated his death sentence. A three-judge panel of this court, however, disagreed that Payton’s penalty phase was fundamentally unfair, reversed the district court, and ordered the writ vacated. Payton v. Woodford, 258 F.3d 905 (9th Cir.2001). We then took this case en banc, adopted the three-judge panel’s decision that there were no guilt phase errors, but affirmed the district court’s decision with respect to the penalty phase. We agreed with the district court that there was error during Payton’s penalty phase, and we affirmed the grant of Payton’s habeas petition. Payton v. Woodford (“Payton I”), 299 F.3d 815 (9th Cir.2002) (en banc).
In our initial en banc opinion, we held that the Antiterrorism and Effective Death Penalty Act of 1996, Pub.L. No. 104-132, 110 Stat. 1218 (April 24, 1996) (“AEDPA”), did not apply to our analysis of Payton’s habeas claims because Payton filed his petition for the appointment of habeas counsel prior to April 24, 1996, the effective date of AEDPA. See Payton, 299 F.3d at 822. In reaching this conclusion, we relied on our prior decision in Calderon v. United States District Court (“Kelly”), 163 F.3d 530, 540 (9th Cir.1998) (en banc), in which we held that a petition for appointment of habeas counsel coupled with a motion for a stay of execution was sufficient for fixing the date for determining when AEDPA applies. After Payton I, the Supreme Court issued its decision in Woodford v. Garceau, 538 U.S. 202, 123 S.Ct. 1398, 1402-03, 155 L.Ed.2d 363 (2003), in which it held that cases are “pending” before the effective date of AEDPA only if a habeas petitioner has filed an “actual application for habeas corpus relief’ in district court; a petition for the appointment of habeas counsel is not enough. In light of its decision in Woodford v. Garceau, the Supreme Court granted a writ of certiorari in Payton I, vacated the judgment, and remanded the case to us for further consideration. See Woodford v. Payton, — U.S. —, 123 S.Ct. 1785, 155 L.Ed.2d 662 (2003).
This opinion (“Payton II”) reflects our decision on remand.1 Here, we apply the [1207]*1207strict AEDPA standard to our analysis of Payton’s habeas claims and conclude, as we did in Payton I, that the district court properly granted Payton’s habeas petition.
BACKGROUND INFORMATION2
In 1980, while spending the night at Patricia Pensinger’s home, Payton raped Pamela Montgomery and stabbed her to death. He then entered the bedroom of Pensinger and her son Blaine, stabbed each of them repeatedly, and fled. Payton was charged with the first degree murder and rape of Montgomery and the attempted murders of Pensinger and her son.
At the guilt phase of Payton’s jury trial, the prosecution presented testimony from the law enforcement officers who observed the crime scene, forensics experts who confirmed that saliva and semen samples taken from Montgomery’s body were consistent with Payton’s, Patricia and Blaine Pensinger who gave victims’ accounts of the attacks, Payton’s wife, who stated that soon after the attacks she saw blood on Payton’s clothes, face, hands and penis as well as fingernail scratches and digs on his legs and back, and a fellow inmate, Alejandro Garcia, who recounted that Payton admitted that he raped and stabbed Montgomery and stabbed the Pensingers because he “had this urge to kill.” The defense called no witnesses, and the jury convicted on all counts.
During the penalty phase, the prosecution presented as a witness a fellow inmate who testified to his jailhouse conversations with Payton in which Payton admitted that he had “severe problems with sex and women,” that he wanted to “stab them and rape them,” and that every “wom[a]n on the street he [saw] was a potential victim, regardless of age or looks.” Payton’s former girlfriend related that she had once awakened to find Payton holding a kitchen knife to her neck, and that he had stabbed her chest and arms. After she pushed him off, he stayed with her and held a towel around her bleeding arm until the police arrived.
The defense presented eight witnesses, including Payton’s pastor, a deputy sheriff, four inmates, his mother, and the director of a religious organization ministering to prisoners. Their testimony, taken as a whole, tended to show that Payton had been “born again,” made a sincere commitment to God, and was performing good works in jail.
Payton’s pastor testified that in his opinion, Payton’s conversion was credible and that he was “sincere in his statement and commitment to the Lord.” The director of a religious outreach organization ministering to prisoners testified to her numerous conversations with Payton about his spiritual commitment and its manifestation in the bible study groups he established with other inmates. She described his conversion of other inmates, his admission to a correspondence bible college, and his writings.
Four inmates testified that they believed that Payton’s religious conversion was sincere and that he had a calming influence on other inmates. One testified that Pay-ton’s intervention prevented him from committing suicide. A deputy sheriff assigned to Payton’s jail facility related that Payton led prayer meetings and had a positive influence on other inmates. Pay-[1208]*1208ton’s mother described praying together with her son and discussing religion on a weekly basis. Asked if she had noticed a change in her son, she responded: “Oh, yes.... He’s totally immersed in the Lord.... He’s an instrument of the Lord as far as he’s concerned.”
Prior to closing arguments in the penalty phase, the judge held an in-chambers conference with the attorneys about the jury instructions. They discussed the application of the multi-factor CALJIC instruction (No. 8.84.1) that guides the jury in determining whether to impose a sentence of life imprisonment or death.3 Factor (k), the eleventh and final factor, directed that the jury consider “[a]ny other circumstance which extenuates the gravity of the crime even though it is not a legal excuse for the crime.” CALJIC 8.84.1. Payton’s counsel sought an amendment to the instruction that expressly would have directed the jury to consider “evidence of the defendant’s character, background, history, mental condition and physical condition.” 4 Although the trial judge agreed with the defense counsel’s interpretation of factor (k), he declined the request because he was reluctant to alter the instruction insofar as it reflected verbatim the text of California Penal Code § 190.3. He stated that he would allow counsel to argue the point. The judge also denied defense counsel’s separate proposal to amend the instruction to permit the jury to consider Payton’s “potential for rehabilitation.”
During closing argument, the prosecutor argued to the jury that factor (k) applied to “some factor at the time of the offense that somehow operates to reduce the gravity for what the defendant did” but that it did not “refer to anything after the fact or [1209]*1209later.” He asserted that factor (k) did not encompass Payton’s conversion to Christianity and good conduct in jail because they occurred “well after the fact of the crime,” and the factor “seems to refer to a fact in operation at the time of the offense.” At one point, the prosecutor said:
What I am getting at, you have not heard during the past few days any legal evidence of mitigation. What you’ve heard is just some jailhouse evidence to win your sympathy, and that’s all. You have not heard any evidence of mitigation in this trial.
Concluding, the prosecutor told the jury that he did not “want to spend too much time on [Payton’s religious conversion] because I don’t think it’s really applicable and I don’t think it comes under any of the eleven factors.”
In response to the prosecutor’s factor (k) argument, the defense moved for a mistrial, objecting that the prosecutor’s argument was “completely contrary to what we all agreed in chambers on the record ‘k’ was designed to apply to.” The court responded that it was a “fair comment on either side” and “I think you can argue it either way.” The court told the jury that “the comments by both the prosecution and the defense are not evidence. You’ve heard the evidence and, as I said, this is argument. And it’s to be placed in its proper perspective.”
Defense counsel’s closing argument acknowledged that factor (k) “may be awkwardly worded.” He argued that the factor was designed as a catch-all to include the kind of evidence in mitigation he had presented, and that, for Payton, it was the most critical of the factors.
After the closing arguments, the judge instructed the jury as noted above. Upon receiving instructions that it must reach a unanimous result, the jury retired to deliberate. The jury returned a verdict of death.
DISCUSSION
I.
Payton filed his habeas petition on May 6, 1996, after the effective date of AEDPA. In light of Woodford v. Garceau, 538 U.S. 202, 123 S.Ct. at 1402, AEDPA therefore applies to our analysis of Payton’s habeas claims.
The California Supreme Court, in a published opinion, addressed the merits of Payton’s factor (k) claims5 and concluded that there was no instructional error at trial. See Payton, 13 Cal.Rptr.2d 526, 839 P.2d at 1049. According to AEDPA, we must determine whether the California Supreme Court’s adjudication of these claims either (1) “resulted in a decision that was contrary to, or involved an unreasonable application of, clearly established Federal law,6 as determined by the Supreme Court [1210]*1210of 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)(1) & (2). The “unreasonable application” prong, which guides our analysis here, “permits a federal habeas court to ‘grant the writ if the state court identifies the correct governing legal principle from this Court’s decisions but unreasonably applies that principle to the facts’ of petitioner’s case.” Wiggins v. Smith, — U.S. —, —-—, 123 S.Ct. 2527, 2534-35, 156 L.Ed.2d 471 (2003) (quoting Williams v. Taylor, 529 U.S. 362, 413, 120 S.Ct. 1495, 146 L.Ed.2d 389 (2000)). “In other words, a federal court may grant relief when a state court has misapplied a ‘governing legal principle’ to ‘a set of facts different from those of the case in which the principle was announced.’” Id. at 2535 (quoting Lockyer, 538 U.S. 63, 123 S.Ct. at 1175). “Unreasonable application” means that the state court’s application of clearly established Supreme Court precedent was “objectively unreasonable.” Id.; see also Lockyer, 538 U.S. 63, 123 S.Ct. at 1175.
We hold that the California Supreme Court unreasonably applied “clearly established” Supreme Court precedent to the facts of this case.
A. Controlling Supreme Court Precedent
“[T]he Eighth and Fourteenth Amendments require that the sentencer, in all but the rarest kind of capital case, not be precluded from considering, as a mitigating factor, any aspect of a defendant’s character or record and any of the circumstances of the offense that the defendant proffers as a basis for a sentence less than death.” Lockett v. Ohio, 438 U.S. 586, 604, 98 S.Ct. 2954, 57 L.Ed.2d 973 (1978) (emphasis in original); see also Eddings v. Oklahoma, 455 U.S. 104, 110, 102 S.Ct. 869, 71 L.Ed.2d 1 (1982); Skipper v. South Carolina, 476 U.S. 1, 4, 106 S.Ct. 1669, 90 L.Ed.2d 1 (1986). That is, the Eighth and Fourteenth Amendments require “individualized consideration of mitigating factors” in capital cases. Lockett, 438 U.S. at 606, 98 S.Ct. 2954; see also Penry v. Lynaugh, 492 U.S. 302, 317, 109 S.Ct. 2934, 106 L.Ed.2d 256 (1989), overruled on other grounds by Atkins v. Virginia, 536 U.S. 304, 122 S.Ct. 2242, 153 L.Ed.2d 335 (2002); Eddings, 455 U.S. at 112, 102 S.Ct. 869. “Relevant mitigating evidence” includes evidence about a defendant’s likely future behavior in prison. See Skipper, 476 U.S. at 7, 106 S.Ct. 1669 (“A defendant’s disposition to make a well-behaved and peaceful adjustment to life in prison is itself an aspect of his character that is by its nature relevant to the sentencing determination.”).
Supreme Court precedent in force at the time the California Supreme Court decided Payton’s factor (k) arguments required that all potentially relevant mitigating evidence—pre-crime and post-crime—be available to the sentencer in a capital case. “Moreover, Eddings makes clear that it is not enough simply to allow the defendant to present mitigating evidence to the sen-tencer. The sentencer must also be able to consider and give effect to that evidence in imposing sentence.” Penry, 492 U.S. at 319, 109 S.Ct. 2934 (emphasis added).
The Supreme Court had occasion to analyze the factor (k) instruction at issue here in Boyde v. California, 494 U.S. 370, 110 S.Ct. 1190, 108 L.Ed.2d 316 (1990). Specifically, the Court addressed “whether petitioner’s capital sentencing proceedings violated the Eighth Amendment because the [1211]*1211trial court instructed the jury in accordance with former CALJIC 8.84.1, including the ‘unadorned’ factor (k).” 494 U.S. at 377, 110 S.Ct. 1190. Boyde contended that factor (k) did not allow the jury to consider and give effect to non-erime-relat-ed mitigating evidence, such as his impoverished and deprived childhood and difficulties in school, because the instruction limited the jury to considering only evidence related to the crime. Id. at 378, 381, 110 S.Ct. 1190. The Court established a standard for reviewing jury instructions that allegedly are “ambiguous and therefore subject to an erroneous interpretation” — “whether there is a reasonable likelihood that the jury has applied the challenged instruction in a way that prevents the consideration of constitutionally relevant evidence.” Id. at 380, 110 S.Ct. 1190. Applying this standard to factor (k), “standing alone,” the Court concluded that “there is not a reasonable likelihood that Boyde’s jurors interpreted the trial court’s instructions to prevent consideration of mitigating evidence of background and character.”7 Id. at 381, 386, 110 S.Ct. 1190.
B. The California Supreme Court’s Application of Controlling Supreme Court Precedent
The California Supreme Court addressed Payton’s argument that “the trial court’s instructions and the prosecutor’s argument led the jurors to believe, incorrectly, that they were not permitted to consider [his] mitigating evidence.” 13 Cal.Rptr.2d 526, 839 P.2d at 1047. The court acknowledged the teachings of Ed-dings, Lockett, and Skipper that the Eighth Amendment requires the sentencer in a capital case to consider evidence of character and background, including “good behavior in prison.” Id. at 1070. In analyzing Payton’s claims, however, it focused entirely on the Supreme Court’s decision in Boyde, id. at 1070-73, which was an unreasonable application of “clearly established” Supreme Court precedent because Boyde does not control this case and, in focusing almost exclusively on Boyde, the court did not give proper effect to clearly established Supreme Court cases such as Skipper and Penry that are controlling here.
Boyde does not control this case for several reasons. First, this case concerns post-crime mitigating evidence such as the evidence the Supreme Court considered in Skipper.8 Boyde, however, addressed whether there was a reasonable likelihood that the jury applied factor (k) in a way that prevented it from considering pre-crime background evidence. The Court relied on “the belief, long held by this society, that defendants who commit criminal acts that are attributable to a disadvantaged background, or to emotional and mental problems, may he less culpable than defendants who have no such excuse.” Id. at 382, 110 S.Ct. 1190 (quoting Penry, 492 U.S. at 319, 109 S.Ct. 2934) (emphasis in original; internal quotation marks omitted). It saw “no reason to believe that reasonable jurors would resist the view, ‘long held by society,’ that in an [1212]*1212appropriate case such evidence would counsel imposition of a sentence less than death.” Id. Whereas there may be no reason to doubt, in light of society’s “long held” views, that a jury would consider a defendant’s pre-crime background in sentencing him, there is reason to doubt that a jury would similarly consider post-crime evidence of a defendant’s religious conversion and good behavior in prison.9
Boyde did not address the question presented here — whether, on its face, the unadorned factor (k) instruction is unconstitutionally ambiguous as applied to post-crime evidence.10 Indeed, the Court explicitly distinguished the character and background evidence at issue there from evidence that “pertain[s] to prison behavior after the crime for which [the petitioner] was sentenced to death, as was the case in Skipper” Boyde, 494 U.S. at 382 n. 5, 110 S.Ct. 1190. Any natural reading of the words of the unadorned factor (k) does not support the inclusion of post-crime evidence because mitigation evidence occurring after a crime cannot possibly “extenuate the gravity of the crime.” Boyde’s conclusions about the plain wording of factor (k) and the instruction’s obvious inclusion of pre-crime background evidence therefore do not apply in this case.
Second, in Boyde, the Court rejected Boyde’s argument that the prosecutor’s comments at sentencing “reinforced an impermissible interpretation of factor (k)” suggesting to the jury that it could not consider Boyde’s mitigating character and background evidence. Id. at 384-85, 110 S.Ct. 1190. The Court reasoned that the prosecutor’s arguments “are usually billed in advance to the jury as matters of argument, not evidence, ... and are likely viewed as the statements of advocates.” Id. at 384, 110 S.Ct. 1190. In addition, “[arguments of counsel which misstate the law are subject to objection and correction by the court.” Id. Key to the Court’s reasoning was the fact that there was “no objectionable prosecutorial argument.” Indeed, the prosecutor never suggested to the jury that it could not consider mitigating evidence of Boyde’s character and background. Id. at 385, 110 S.Ct. 1190. The prosecutor “explicitly assumed that petitioner’s character evidence was a proper factor in the weighing process.” Id. (emphasis added).
Whereas the prosecutor in Boyde conceded that the jury must consider Boyde’s mitigating character and background evidence, the prosecutor here repeatedly stated to the jury that factor (k) did not encompass Payton’s mitigating evidence of his religious conversion and good behavior in prison.11 For example, after listing the eleven factors in CALJIC 8.84.1, the pros[1213]*1213ecutor gave his interpretation of factor (k) to the jury:
‘K’ says any other circumstance which extenuates or lessens the gravity of the crime. What does that mean? That to me means some fact ... some factor at the time of the offense that somehow operates to reduce the gravity for what the defendant did. It doesn’t refer to anything after the fact or later. That’s particularly important here because the only defense evidence you have heard has been about this new bom Christianity. (emphasis added)
After the court overruled the defense attorney’s objection to the legal misstatements in the prosecutor’s argument, the prosecutor continued arguing to the jury:
Referring back to ‘K’ which I was talking about, any other circumstance which extenuates or lessens the gravity of the crime, the only defense evidence you’ve heard had to do with Defendant’s new Christianity and that he helped the module deputies in the jail while he was in custody. The problem with that is that evidence is well after the fact of the crime and cannot seem to me in any way to logically lessen the gravity of the offense that the defendant has committed. [The defense] will tell you that somehow that becoming a newborn Christian, if in fact he really believed that took place, makes it a less severe crime, but there is no way that can happen when — under any other circumstance which extenuates or lessens the gravity of the crime, refers — -seems to refer to a fact in operation at the time of the offense. What I am getting at, you have not heard during the past few days any legal evidence [of] mitigation. What you’ve heard is just some jailhouse evidence to win your sympathy, and that’s all. You have not heard any evidence of mitigation in this trial, (emphasis added)
He then specifically told the jury that it had not “heard anything to mitigate what [Payton’s] done” and that Payton’s only mitigating evidence did not fit into factor (k):
I want to make a few comments about religion, the only evidence put on by the defendant. I don’t really want to spend too much time on it because I don’t think it’s really applicable and I don’t think it comes under any of the eleven factors. ... (emphasis added)12
Indeed, the prosecutor focused the jury’s attention on the eleven CALJIC factors, which he argued did not encompass Pay-ton’s mitigating evidence:
You shall consider, take into account and be guided by the applicable factors of aggravating and mitigating circumstances upon which you have been instructed. In other words, the factors I have just read to you.
* * * *
The jury is expected or supposed to go through a weighing process of the factors I have just described, (emphasis added)
The California Supreme Court recognized that the prosecutor “suggested a narrow and incorrect interpretation of factor (k),” but it reasoned that “[a]ny impact this argument may have had ... was immediately blunted by defense counsel’s objection, which led the court to remind the jury that lawyers’ comments were ‘not evidence’ but ‘argument,’ and ‘to be placed in [their] proper perspective.’ ” 13 13 Cal. [1214]*1214Rptr.2d 526, 839 P.2d at 1048. This was an unreasonable application of Boyde.14
According to Boyde, “the arguments of counsel, like the instructions of the court, must be judged in the context in which they are made.” 494 U.S. at 385, 110 S.Ct. 1190. In Boyde, the factor (k) instruction potentially was ambiguous but the prosecutor correctly stated in his argument that the jury must consider Boyde’s mitigating character and background evidence, thus clarifying the scope of the instruction. Here, however, the jury was confronted with an ambiguous factor (k) instruction and with post-crime mitigating evidence that, unlike the pre-crime character and background evidence in Boyde, did not fit clearly within the plain wording of the instruction. On top of this, the court explicitly authorized the prosecutor to argue that Payton’s post-crime mitigating evidence could not be considered under factor (k), overruled defense counsel’s objection to the prosecutor’s legal misstatements, and failed to instruct the jury that it must consider and give effect to Payton’s post-crime mitigating evidence.15 This is not a [1215]*1215case in which the prosecutor made an offhand remark during the course of trial. The prosecutor’s erroneous argument was far from subtle. It was explicit, deliberate, consistent, and repeated. Indeed, the jury was presented with the prosecutor’s and the defense attorney’s conflicting arguments about whether it legally could consider Payton’s mitigating evidence under factor (k),16 and the court left it up to the jury to choose which version of the law to apply. When the court expressly permits counsel to argue the legal meaning of an instruction, without ever instructing the jury which interpretation is correct, the arguments of counsel obviously take on significant importance. A lay jury is ill-equipped to determine which view of the law is correct.17 See Griffin v. United States, 502 U.S. 46, 59, 112 S.Ct. 466, 116 L.Ed.2d 371 (1991) (“When ... jurors have been left the option of relying upon a legally inadequate theory, there is no reason to think that their own intelligence and expertise will save them from that error.”); Penry, 492 U.S. at 328, 109 S.Ct. 2934 (“ When the choice is between life and death, that risk [that the death penalty will be imposed in spite of factors which may call for a less severe penalty] is unacceptable and incompatible with the commands of the Eighth and Fourteenth Amendments.’ ” (quoting Lockett, 438 U.S. at 605, 98 S.Ct. 2954)).
In this context, there was a reasonable likelihood that, as a result of the prosecutor’s legally erroneous arguments and the court’s failure to correct the arguments with proper jury instructions, the jury did not consider and give effect to the post-crime mitigating evidence of Payton’s religious conversion and good behavior in prison. This was constitutional error. See Penry, 492 U.S. at 326, 109 S.Ct. 2934 (reversing a death sentence and remanding for resentencing because, on the basis of the prosecutor’s argument and the absence of appropriate jury instructions, “a reasonable juror could well have believed that there was no vehicle for expressing the view that Penry did not deserve to be sentenced to death based upon his mitigating evidence”); Skipper, 476 U.S. at 5, 106 S.Ct. 1669 (holding that post-crime evidence that a defendant would not pose a danger in prison “must be considered po[1216]*1216tentially mitigating” and “may not be excluded from the sentencer’s consideration”); Eddings, 455 U.S. at 114-15, 102 S.Ct. 869 (holding that the sentencer in a capital case may not “refuse to consider, as a matter of law, any relevant mitigating evidence” and may not give such evidence “no weight”); Lockett, 438 U.S. at 608, 98 S.Ct. 2954 (striking down Ohio’s death penalty statute as violating the Eighth and Fourteenth Amendments due to its “limited range of mitigating circumstances which may be considered by the sentencer” and its preclusion from consideration of other relevant mitigating factors). The California Supreme Court’s conclusion to the contrary, on the basis of Boyde, which did not address improper legal argument by a prosecutor or a court’s failure to provide jury instructions to correct the attorney’s legally erroneous argument, was an unreasonable application of “clearly established” Supreme Court precedent. When the effect of a mitigation instruction, viewed in the full context of the trial, is to confuse or mislead the jury in its duty to consider all relevant mitigation evidence, there has been constitutional error.
II.
In light of our conclusion that there was constitutional error, we must now decide whether this error was harmless. We hold that the error was not harmless because it had a “substantial and injurious effect or influence” on the jury’s verdict, Brecht v. Abrahamson, 507 U.S. 619, 623, 113 S.Ct. 1710, 123 L.Ed.2d 353 (1993), and we are left with “grave doubt” as to the harmlessness of the error, O’Neal v. McAninch, 513 U.S. 432, 435, 115 S.Ct. 992, 130 L.Ed.2d 947 (1995).
As an initial matter, we note that our caselaw is not clear as to whether the petitioner, the state, or neither, bears responsibility for demonstrating the significance of the error under the Brecht/O’Neal harmlessness standard. Compare Rodriguez v. Marshall, 125 F.3d 739, 744 (9th Cir.1997) (stating that petitioner bears the burden of showing harm); Franklin v. Henry, 122 F.3d 1270, 1273 (9th Cir.1997) (same); with Keating v. Hood, 191 F.3d 1053, 1062 (9th Cir.1999) (as amended) (noting that the state bears the burden of showing harmlessness); Fisher v. Roe, 263 F.3d 906, 917 (9th Cir.2001) (same); and with Mancuso v. Olivarez, 292 F.3d 939, 949 n. 4 (9th Cir.2002) (as amended) (attempting to clarify the inconsistency in our caselaw regarding burdens of proof and concluding that “the reviewing court must determine independently whether a trial error had a substantial and injurious effect, without consideration of burdens of proof’); Thompson v. Borg, 74 F.3d 1571, 1575 (9th Cir.1996) (rejecting burdens of proof in favor of an independent determination of whether a trial .error had a substantial and injurious effect).
It is clear from O’Neal that the petitioner does not bear the burden of showing harm. 513 U.S. at 436, 115 S.Ct. 992 (“[W]e note that we deliberately phrase the issue in this case in terms of a judge’s grave doubt, instead of in terms of ‘burden of proof.’ ”) (emphasis added). Because the harmless error analysis is a purely legal question that lies outside the realm of fact-finding, we dispense with burdens of proof and presumptions. See id. at 437, 115 S.Ct. 992 (explaining that the court must determine whether the error affected the judgment “without benefit of such aids as presumptions or allocated burdens of proof that expedite fact-finding at the trial” (quoting R. Traynor, The Riddle of Harmless Error 26 (1970))). O’Neal directs us to ask a “conceptually clearer” question in reviewing the record in a habeas case: “ ‘Do I, the judge, think that the error substantially influenced the jury’s decision?’ ” Id. at 436, 115 S.Ct. 992.
In asking this question, we step back to determine where we are on the spectrum [1217]*1217of certainty about the harmlessness of the constitutional error. If we are convinced that “the error did not influence the jury, or had but very slight effect, the verdict and the judgment should stand.” Id. at 437, 115 S.Ct. 992 (quoting Kotteakos v. United States, 328 U.S. 750, 764-65, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946)). If, on the other hand, we are not fairly assured that there was no effect on the verdict, we must reverse. Id. In the “narrow circumstance” in which we are in “grave doubt” as to the effect of the constitutional error, we must assume that there was such an effect, and grant the petition. O’Neal, 513 U.S. at 436, 438, 115 S.Ct. 992; see also Thompson, 74 F.3d at 1575.
In the course of this inquiry, it is the State that bears the “risk of doubt.” O’Neal, 513 U.S. at 438, 115 S.Ct. 992; Valerio v. Crawford, 306 F.3d 742, 762 (9th Cir.2002) (en banc), cert. denied, — U.S. -, 123 S.Ct. 1788, 155 L.Ed.2d 695 (2003). We look to the State to instill in us a “fair assurance” that there was no effect on the verdict. See Morales v. Woodford, 336 F.3d 1136, 1148 (9th Cir.2003) (“[T]he state must provide us with a ‘fair assurance’ that the error was harmless under Brecht.”); Valerio, 306 F.3d at 762; see also O’Neal, 513 U.S. at 443, 115 S.Ct. 992 (“[T]he State normally bears responsibility for the error that infected the initial trial.”). Only if the State has persuaded us that there was no substantial and injurious effect on the verdict do we find the error harmless.
This framework is faithful to the balance the Supreme Court has struck between concerns of federal-state comity and finality in state criminal trials, and the irreversible harm caused by an execution resulting from an unconstitutional error. In weighing these concerns in a non-capital case, the Supreme Court stated:
[T]he number of acquittals "wrongly caused by grant of the writ and delayed retrial (the most serious harm affecting the State’s legitimate interests) will be small when compared with the number of persons whom this opposite rule (denying the writ) would wrongly imprison or execute. On balance, we must doubt that the law of habeas corpus would hold many people in prison “in violation of the Constitution,” for fear that otherwise a smaller number, not so held, may eventually go free.
O’Neal, 513 U.S. at 443, 115 S.Ct. 992. Placing the “risk of doubt” on the state is also consistent with the body of jurisprudence that has placed the burden of showing lack of prejudice on the party who would benefit from the constitutional error. Id. at 437-44, 115 S.Ct. 992; United States v. Olano, 507 U.S. 725, 741, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993) (stating that the government bears the “burden of showing the absence of prejudice”); Chapman v. California, 386 U.S. 18, 24, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967) (noting that “the original common-law harmless-error rule put the burden on the beneficiary of the error ... to prove that there was no injury”). Kotteakos, which articulated the harmlessness standard that Brecht later adopted and that we now apply, “places the burden on prosecutors to explain why those errors were harmless.” Brecht, 507 U.S. at 640, 118 S.Ct. 1710 (Stevens, J., concurring).18
Considering the record before us, the State has not provided us with a “fair [1218]*1218assurance” that the error did not prejudice the penalty phase of Payton’s trial. O’Neal, 513 U.S. at 437-38, 115 S.Ct. 992; Valerio, 306 F.3d at 762. On one side of the balance sheet is the State’s evidence of aggravating circumstances. There is no question that this was a brutal crime. The prosecution introduced eyewitnesses to Payton’s actions, testimony as to his motives and character, and forensic and other evidence to demonstrate to the jury the devastating effects of the crime.
It is the other side of the balance sheet that undermines any assurance that the jury’s verdict was not affected. As required by California Penal Code § 190.3, the trial court further instructed the jury that “If you conclude that the aggravating circumstances outweigh the mitigating circumstances, you shall impose a sentence of death.” We have determined that there is a reasonable likelihood that the jury accepted the prosecutor’s erroneous statement of the law rather than the defense counsel’s and that it therefore failed to consider the only evidence offered in mitigation of the death penalty. That left the jury bereft of any countervailing evidence to weigh against the prosecution’s evidence of aggravating circumstances.
We cannot know whether the jury would have returned a verdict of life or of death had it been properly instructed. Payton’s extensive evidence of his conversion to Christianity, positive influence on other inmates, and other good works in jail were offered to evoke to the jury his potential for rehabilitation.19 If the jury had been inclined to weigh favorably evidence of redeeming features of his character or his conduct while in custody pending trial, it would have felt constrained by law from considering that evidence. Without Pay-ton’s mitigating evidence, the jury was bound by California Penal Code § 190.3 to impose a death sentence. See Easley, 196 Cal.Rptr. 309, 671 P.2d at 827.
Having pondered “all that happened without stripping the erroneous action from the whole,” O’Neal, 513 U.S. at 437, 115 S.Ct. 992 (quoting Kotteakos, 328 U.S. at 764-65, 66 S.Ct. 1239), we do not arrive at a fair assurance that the error was harmless. As we have previously stated, “[b]ecause a death sentence is qualitatively different from other forms of punishment, there is a greater need for reliability in determining whether it is appropriate in a particular case.” Coleman v. Calderon, 210 F.3d 1047, 1050 (9th Cir.2000); see also Mills v. Maryland, 486 U.S. 367, 376, 108 S.Ct. 1860, 100 L.Ed.2d 384 (1988) (“In reviewing death sentences, the Court has demanded even greater certainty that the jury’s conclusions rested on proper grounds.”). Far from a fair assurance that the error was harmless, the “possible jury confusion” arising from the trial court instruction leaves us in “grave doubt about the likely effect of [the] error on the jury’s verdict.” O’Neal, 513 U.S. at 435, 115 S.Ct. 992; see also Fisher, 263 F.3d at 917-18. We therefore conclude that the instructional error had a “substantial and injurious effect or influence on the jury’s verdict” that necessitates a new penalty phase trial. Payton is entitled to a penalty trial before a jury that is properly instructed that it must take his post-crime evidence into account in determining whether to impose a sentence of life or death.
[1219]*1219CONCLUSION
Accordingly, we AFFIRM the judgment of the district court granting Respondent’s motion for summary judgment as to all claims except Claim IVB, item 3 of the petition for habeas corpus, and granting the writ of habeas corpus as to the penalty phase of the trial.
AFFIRMED.