Full opinion text
Opinion by Judge THOMAS; Concurrence by Judge REINHARDT; Dissent by Judge RAWLINSON. THOMAS, Circuit Judge. In this appeal we consider whether the district court erred in denying a writ of habeas corpus sought as to petitioner’s conviction and death sentence. We affirm the district court’s judgment as to the conviction. However, we conclude that the Supreme Court’s decision in Ring v. Arizona, 536 U.S. 584, 122 S.Ct. 2428, 153 L.Ed.2d 556 (2002), applies retroactively so as to require that the penalty of death in this case be vacated. I It is the raw material from which legal fiction is forged: A vicious murder, an anonymous psychic tip, a romantic encounter that jeopardized a plea agreement, an allegedly incompetent defense, and a death sentence imposed by a purportedly drug-addled judge. But, as Mark Twain observed, “truth is often stranger than fiction because fiction has to make sense.” There is no doubt that Warren Summer-lin is an extremely troubled man. He has organic brain dysfunction, was described by a psychiatrist as “functionally retarded,” and has explosive personality disorder with impaired impulse control. His father was a convicted armed robber who was killed in a shootout. As a youth, his alcoholic mother beat him frequently and punished him by locking him in a room with ammonia fumes. At his mother’s behest, he received electroshock treatments to control his explosive temper. He dropped out of school in the seventh grade due to dyslexia and committed numerous petty juvenile offenses. In 1975, he was diagnosed as a paranoid schizophrenic and treated with the anti-psychotic medication Thorazine. Before his murder conviction, his only dangerous adult felony was a conviction for aggravated assault. That conviction arose out of a road rage incident in which a car veered off the road, jumped the curb and struck Summerlin’s wife, who was hospitalized for her injuries. At the scene, Sum-merlin brandished a pocket knife at the errant driver, an act that occasioned the filing of the criminal assault charge. Sum-merlin was not convicted of this offense until after these capital proceedings had commenced. However, this conviction later served as one of two statutory aggravating factors that qualified Summerlin for the death penalty. On the morning of April 29, 1981, Bren-na Bailey, a delinquent account investigator for Finance America, went to Summer-lin’s home to speak with Summerlin’s wife about an overdue account. When Bailey’s boyfriend, Marvin Rigsby, learned that she had not returned to work as scheduled, he obtained the addresses of the places she had planned to visit that day and began to retrace her travel. In the early evening, he spoke with Summerlin, who told Rigsby that Bailey had left that residence at 10:30 a.m. The woman residing at the next address Bailey was slated to visit told Rigsby that she had been home all day and had not received a visit from anyone. After making additional attempts to find Bailey, Rigsby reported Bailey’s disappearance to the police that evening. Later that evening, the police received a tip from a female caller to an anonymous crime hotline service who stated that she believed that the missing woman from “Pacific Finance Company” had been murdered by Summerlin, who had rolled up the victim’s body in a carpet. The caller later was identified as Summerlin’s mother-in-law who testified that the basis of her information was her daughter’s extra-sensory perception. Early the next morning, a road paving crew outside a market approximately a mile from the Summerlin residence alerted the market’s manager to a smell emanating from the trunk of a parked car, later determined to have been owned by Bailey. The manager recognized the odor as that of a decaying body and telephoned the police. Upon arrival, the officers observed a pair of panties, pantyhose, and shoes on the floor-board of the back seat. They forced open the trunk and found Bailey’s body, wrapped in a bloody bedsheet. Her skull was crushed, and she was partially nude. The police obtained a search warrant for the Summerlin residence and found numerous items of incriminating evidence. After the search warrant was read to Sum-merlin, he stated, “I didn’t kill nobody.” When the detective did not respond, Sum-merlin asked: “Is this in reference to the girl that was at my house?” In response to the officer’s inquiry as to which girl he was referring, Summerlin described Bailey. Summerlin’s wife identified the bloody bedspread found with the victim as belonging to the Summerlin household. Summerlin was then arrested for the murder of Brenna Bailey. At the police station, Summerlin asked to speak to his wife and then made several incriminating statements while police officers were within listening distance. The state trial court appointed the public defender’s office to represent Summer-lin. The' first attorney assigned to the case moved for a mental competency examination pursuant to Ariz. R.Crim. P. 11. Thereafter, the assigned attorney left the public defender’s office, and an attorney whom we shall refer to as “Jane Roe” was designated to represent Summerlin. In Juné 1981, Summerlin was examined by two court-appointed psychiatrists, Drs. Maier Tuehler and Ótto Bendheim. Each found him competent to stand trial and legally sane under the M’Naghten standard, which then governed the determination of competency under Arizona law. Although there was no evidence of mental disease or defect, Dr. Tuehler observed that dyslexia and illiteracy made Summer-lin “functionally mentally retarded.” He further found that Summerlin’s impulse control was extremely impaired due to an explosive-type personality disorder and that he had an anti-social personality. Upon reading the reports, Judge David G. Derickson found Summerlin competent to stand trial. During this time period, Roe had conversations with Dr. Leonardo Garcia-Bunuel, a psychiatrist who treated Summerlin at the Maricopa County Jail, regarding a possible diagnosis of psychomotor epilepsy. Summerlin had described to Dr. Garcia Buñuel details of the murder, particularly his experiences of sensing an intense perfume odor, and this led Dr. Garcia Buñuel to suspect that Summerlin may have had a temporal lobe seizure at the time of the killing. Subsequently, in August 1981, Roe arranged for neurological testing by Dr. Mark Winegard. An electroencephalogram (EEG) showed some slowing in Sum-merlin’s posterior temporal area but was insufficient to support a diagnosis of epilepsy. CAT scans and a second EEG performed in October 1981 were normal. As a result, Dr. Garcia Buñuel withdrew his concerns. Roe also secured a psychological evaluation of Summerlin from Dr. Donald Tatro in November 1981. Although concluding there was no evidence to support an insanity defense, Dr. Tatro found indications of organic brain impairment, border-line personality disorder, and paranoid personality disorder. In Dr. Tatro’s opinion, Summer-lin “is deeply emotionally and mentally disturbed, unaware of the motives underlying much of his behavior, and unable, because of his problems, to exercise normal restraint and control, once his highly unstable and volatile emotions are aroused.” In November 1981, Roe began plea negotiations with the prosecution and obtained an extremely favorable plea agreement, which Summerlin entered into on November 17, 1981. The prosecutor, whom we will call “John Doe,” had been willing to enter into the agreement because he did not believe that the offense satisfied the Arizona legal standard of “heinous, cruel and depraved.” At the time, Summerlin had not been convicted of the aggravated felony arising out of the road rage incident, so it did not qualify as an aggravating factor under Arizona’s capital sentencing statute. See Ariz.Rev.Stat. § 13 — 703(F)(2) (1981) (amended in 1993). Thus, Doe did not believe that Summerlin had committed a capital offense. Under the proposed plea agreement, Summerlin was to enter an Alford plea, see North Carolina v. Alford, 400 U.S. 25, 91 S.Ct. 160, 27 L.Ed.2d 162 (1970), which enabled him, without admitting guilt, to plead guilty to second-degree murder and aggravated assault and to be sentenced accordingly. The agreement stipulated that Summerlin would be sentenced to twenty-one years in prison for the murder of Ms. Bailey, of which he would be required to serve fourteen. In exchange, Summerlin would plead guilty to aggravated assault for the road rage incident with a maximum sentence of fifteen years and would, admit that he violated his probation in another case charging burglary. The plea agreement provided that Summerlin’s sentences on the three charges would run concurrently. However, the agreement was subject to court approval. If the court rejected the stipulated sentence, Summer-lin could either (1) allow his plea to stand and be sentenced to a term of up to thirty-eight-and-one-half years, according to the court’s sole discretion, or (2) withdraw from his plea of guilty and have the matters proceed to trial and disposition. On the day he entered the plea, Sum-merlin properly answered all the questions required to validate his Alford plea. He had second thoughts a few days later, however, and formally sent to the court a pro se motion to withdraw his plea and to fire his public defender. In a court appearance on December 15, 1981, scheduled to address his motion, Summerlin openly registered dissatisfaction with the plea, the stipulated sentence, and Roe’s handling of his case. After hearing his complaints, Judge Derickson denied Summerlin’s motions, but took the occasion to inform Summerlin that it was his intention on the upcoming sentencing date not to accept the stipulated sentence. Therefore, Summerlin would have the option either to withdraw from the plea or to allow it to stand and be sentenced accordingly. Realizing that her client’s intention to withdraw from the agreement might again make him eligible for the death penalty, Roe promptly attempted to have the case transferred to another judge who might look more favorably on the deal. On December 18, 1981, the presiding judge denied her motion to disqualify Judge Der-ickson on the ground of prejudice towards her client and allowed Judge Derickson to continue with the case. That same evening, Roe attended a Christmas party. She and prosecutor Doe left the party together and had'what she later described as a “personal involvement ... of a romantic nature.” As a result of that, as she later testified, she felt she “could no longer ethically represent Mr. Summerlin.” Because of the circumstances, she believed “that it would be appropriate for another Public Defender to handle the case and take it to trial, since it looked like it might be a trial at that point, because Mr. Summerlin indicated he wanted a trial and Judge Derickson had indicated he was going to reject the plea.” She reported the situation to her supervisor, and it was determined that the entire office probably was compromised. Notwithstanding her belief that she could not represent Summerlin due to a personal conflict of interest, Roe took no immediate steps to accomplish her withdrawal. Neither she nor her office informed either the court or their client of her conclusion that she could no longer be Summerlin’s attorney. Instead, she accompanied him to and represented him at the next hearing before Judge Derickson on December 22,1981. At the hearing, Judge Derickson advised Summerlin of his decision not to be bound by the sentencing part of the plea agreement, and that if Summerlin allowed his plea to stand, he was facing up to thirty-eight-and-one-half years in prison for the three offenses. After some confusion during which Summerlin told the court twice that he did not understand the Judge’s explanation of the sentence he now might face, Roe privately conferred with her client. Their discussion ended with Roe’s statement to the court, “I believe he understands, your Honor.” Summerlin’s immediate response was, “No, I don’t understand,” to which Roe replied, “Then what is your question?” Summerlin then asked about the number of years he might face on the three charges. Judge Derickson explained again the sentence that Sum-merlin would face if he permitted his plea to stand. To this Summerlin said that he finally understood, adding, “Okay. I would like to withdraw from my plea agreement. Is that what you want me to say?” Judge Derickson appropriately told Summerlin that he did not “want” Summerlin to say that, he simply wanted to make sure that Summerlin understood what would happen if he permitted the plea to stand. This exchange prompted another confidential discussion between Summerlin and Roe, followed by Summerlin’s statement that, “It says, if this plea agreement should be changed in any way, I can withdraw.” “Yes, that’s the question he asked you,” Roe replied. Summerlin then withdrew from the agreement. The court immediately reinstated his pleas of not guilty to the two consolidated cases, vacated its findings in the pending probation violation matter, and ordered that the matters be sent to the presiding judge for trial setting. Summerlin’s courtroom decision to withdraw his plea made him eligible for a conviction of first-degree murder and a sentence of death. At this point in the hearing, Summerlin moved once again for new counsel. Roe remained silent. The court denied his motion, stating that “the record may further reflect that you failed to establish any grounds upon which counsel should be changed.” Judge Derickson later submitted an affidavit indicating that had he then known of the conflict, he would have granted Summerlin’s request to change counsel and would have continued the proceeding rather than proceeding with the plea colloquy- On December 28, 1981, six days after Summerlin withdrew his plea, Roe finally broached the problem with Doe. On behalf of her client, she wanted Doe to stay on the case because he favored disposing of it with a lesser plea. He could discern no reason to step down as the prosecutor. After this discussion, a hearing was arranged for December 28, 1981, at which Roe planned to move to withdraw as counsel and to permit the rest of the Public Defender’s Office to withdraw also. By this time, the case had been assigned to another judge, Judge Riddel, for trial. On December 28, Judge Riddel’s calendar was being handled by Judge McCarthy. Roe did not inform Summerlin of her intent to seek withdrawal or of the conflict that had precipitated her decision. At the hearing, Judge McCarthy began by noting that it had been “brought to the attention of the Court that defendant Mr. Summerlin is dissatisfied with the legal representation he is presently receiving.” The judge asked Summerlin if that was correct, to which Summerlin responded, “Yes, sir.” The judge then noted that he had spoken with counsel in chambers “and apparently it is their feeling that it would be in the best interest of justice that new counsel be appointed.” Judge McCarthy then appointed George Klink, a private practitioner, as new counsel. Following the reassignment of counsel, Roe did not advise Summerlin of her conflict of interest because she saw “no reason to beat a dead horse.” Klink then assumed representation of Summerlin in both of the charges stemming from Bailey’s murder and in the separate charge of aggravated assault arising out of the road rage incident, which was unrelated to the murder. Approximately six weeks later, the Arizona Attorney General’s Office assumed control of the prosecution due to the conflict of interest between Doe and Roe. The Attorney General made it plain that the case would not be settled by way of a lesser plea. Klink filed a motion disqualifying Judge Riddel, and Summerlin’s murder case was then assigned to Judge Philip Marquardt. Klink had intended to disqualify Judge Riddel as to the separate aggravated assault charge filed on the basis of the road rage incident. However, he failed to take the appropriate measures to accomplish this aim. After discovering this, Klink moved for a continuance of the assault trial because he was unprepared. His motion was denied and the assault trial proceeded. Klink called only one witness, Summerlin’s wife. Summerlin was convicted of aggravated assault and this conviction served several months later as one of the two aggravating circumstances in the penalty phase of his murder trial. Klink spoke with Roe about the murder case and the medical reports. However, he never spoke with any of the experts who had interviewed Summerlin. He attempted to get another psychiatric expert, but he failed. Klink’s main defense theory for the murder trial was Summerlin’s putative lack of premeditation. Klink presented no evidence supporting that theory. He cross-examined several prosecution witnesses in an attempt to east reasonable doubt on the rape charge as a way of proving lack of premeditation. Because the prosecution offered no psychiatric evidence, Klink could not cross-examine anyone regarding Summerlin’s psychiatric problems and how they would affect his ability to premeditate the murder. Klink called only one witness, Roe, and he only asked her a few questions in order to impeach one of the coroner’s statements regarding the length of time seminal fluid remains in the body. The entire case lasted only four days, and the jury was out for a little over three hours. The jury found Summerlin guilty of both first-degree murder and sexual assault. The judge set a sentencing hearing to hear testimony and argument on aggravating and mitigating circumstances approximately one month after the verdict. In that month, Klink never met with Sum-merlin. Klink knew that the prosecution planned to call Drs. Tuchler and Bendheim at sentencing, but he never contacted either of them. Klink knew that Summerlin had been convicted of only one dangerous felony — the aggravated assault that Klink had tried before another judge. He also knew of mitigating circumstances surrounding that assault, including that the victim was not physically harmed and that Summerlin’s reaction was in response to witnessing the woman striking his wife with her car. Klink nonetheless did not present this information to the judge. Klink prepared no evidence regarding Summerlin’s social history despite references in Dr. Tatro’s report that Summerlin possibly experienced severe physical and emotional abuse in his childhood. The sentencing hearing commenced on the afternoon of July 8, 1982. It was an extremely short proceeding, extending only twenty-six transcript pages, more than half of which constituted colloquy between counsel and the court. The court first entertained argument on the defense motion for a new trial, which the judge indicated he would consider over the weekend. The State’s aggravation case consisted of only one exhibit, specifically certified copies of documents relating to the aggravated assault conviction. The State then asked the judge to consider the trial testimony and rested its case. The entirety of the State’s aggravation case was recorded in one page of transcript. For the defense case in mitigation, Klink called Dr. Tatro to the stand. However, before the witness could be sworn in, Sum-merlin interrupted and — although the conversation is not in the trial transcript— apparently requested that his attorney not present Dr. Tatro. Klink requested a five-minute recess, at the conclusion of which he stated: iCWith the consent of the Defendant, the Defendant has no witnesses in mitigation at this time and ... we’ll rest.” The judge then reminded Klink and Sum-merlin that this was the time set aside for the aggravation and mitigation hearing and that he planned to proceed with sentencing the next Monday. The judge then said, “so you tell me that you have one witness that you may present on Monday?” Klink replied: “Well, I would not call any witnesses at all.” The judge then indicated that he would allow Summerlin to make any statement that he wished to make, either at the present hearing or on Monday. Subsequently in the hearing, Klink noted that he would rely on the written report of Dr. Tatro attached to the presentence report. The State proceeded by presenting two rebuttal psychiatric witnesses. Judge Marquardt advised the parties that he would deliberate over the weekend and announce his decision on Monday. Unbeknownst to Summerlin, Judge Mar-quardt was a heavy user of marijuana at the time, a fact that the State conceded in the federal habeas proceedings before the district court in this case. The amount of marijuana that Judge Marquardt may have used during the trial or deliberations is unknown because the district court did not allow discovery on this issue, although there is record support for Summerlin’s claim that Judge Mar-quardt was either having difficulty concentrating or experiencing short-term memory loss. In any event, Judge Marquardt adjourned the penalty phase proceedings on Friday, indicating that he would deliberate over the sentence during the weekend and would also consider the motion for a new trial. However, on Monday, he either forgot or elected not to rule on the motion for a new trial and immediately proceeded with sentencing. Judge Marquardt began the hearing simply by announcing the case and inquiring whether Summerlin had anything to say or legal cause to show why judgment and sentence should not be pronounced. Klink stated he knew of no legal cause. Summerlin stated that he had a motion to vacate the judgment for the judge to consider. The judge examined the motion, took a five-minute recess, then denied it. The judge then heard brief oral arguments from the State and from Klink. He neither asked Summerlin whether he had anything further to say nor advised him of his right to allocution with respect to the sentence. Judge Marquardt then sentenced Sum-merlin to death after finding two aggravating circumstances and no sufficiently substantial mitigating circumstances. The judge based his decision as to aggravating circumstances on two statutory grounds: (1) that the defendant had a prior felony conviction involving the use or threatened use of violence on another person, Ariz. Rev.Stat. § 13-703(F)(2) (1981) (amended in 1993); and (2) that Summerlin committed the offense in an especially heinous, cruel, or depraved manner, id. § 13-703(F)(6). He found no mitigating circumstances. The same day, Judge Marquardt also sentenced James Clifford Fisher to death. Fisher had been charged with murdering Marguerite Bailey — no relation to Brenna Bailey — -with a blunt instrument. See State v. Fisher, 141 Ariz. 227, 686 P.2d 760, 758 (1984). As in the case with Sum-merlin, Judge Marquardt found two aggravating circumstances (including that the victim had been killed in an especially heinous and depraved manner) and no mitigating circumstances sufficiently substantial to call for leniency. Id. at 775-76. Fisher eventually received post-conviction relief on the basis of an unethical plea agreement that Judge Marquardt expressly entered into as a party and subsequently allowed into evidence at trial. See State v. Fisher, 176 Ariz. 69, 859 P.2d 179, 184 (1993). Summerlin alleges that Judge Marquardt confused some of the facts between the cases during Summerlin’s sentencing healing. The Supreme Court of Arizona reviewed and affirmed Summerlin’s convictions and his sentence. See State v. Summerlin, 138 Ariz. 426, 675 P.2d 686 (1983), recons. den. Jan. 17, 1984. After an initial petition for writ of habeas corpus in federal district court and four unsuccessful post-conviction attempts in state court to overturn his conviction, Summerlin filed a second amended petition for writ of habeas corpus in the federal district court in Arizona on November 22, 1995. See 28 U.S.C. § 2254 (1994). The federal district court denied Summerlin’s second amended petition for writ of habeas corpus on October 31, 1997. Pursuant to Fed.R.Civ.P. 59(e), Summerlin moved to vacate the judgment on November 28, 1997. The district court denied this motion on January 12, 1998. However, the district court issued a certificate of probable cause enabling Summerlin to appeal pursuant to Fed. R.App. P. 22(b)(1). This timely appeal followed. A divided three-judge panel of this Court issued its opinion on October 12, 2001, affirming the district court in part and reversing in part. See Summerlin v. Stewart, 267 F.3d 926 (9th Cir.2001). The case was remanded for an evidentiary hearing as to whether Judge Marquardt was competent when he was deliberating on whether to impose the death penalty. Id. at 957. In the meantime, the United States Supreme Court granted certiorari in State v. Ring, 200 Ariz. 267, 25 P.3d 1139 (2001), cert. granted, 534 U.S. 1103, 122 S.Ct. 865, 151 L.Ed.2d 738 (2002), which involved a potential reexamination of Arizona’s death penalty statute in light of the Sixth Amendment. Because this was an issue that had been raised by Summerlin in his state and federal court petitions, the panel withdrew its decision and deferred submission of the case pending the Supreme Court’s resolution of Ring. See Summerlin v. Stewart, 281 F.3d 836, 837 (9th Cir. 2002). Later that year, the Supreme Court issued its decision in Ring v. Arizona, holding that Arizona’s capital sentencing scheme was incompatible with the Sixth Amendment right to a trial by jury. 536 U.S. at 609, 122 S.Ct. 2428. Following the Supreme Court’s Ring decision, Summerlin moved to stay the proceedings in this case. Summerlin desired the stay so that he could request that the Arizona Supreme Court recall the mandate in his direct appeal to consider Ring’s application to his case. Such a procedure is cognizable under Arizona state law. See Lindus v. N. Ins. Co. of N.Y., 103 Ariz. 160, 438 P.2d 311, 313 (1968) (describing doctrine); see also State v. Ariz. Dep’t of Corrs., 187 Ariz. 211, 928 P.2d 635, 636 (1996) (applying procedure to consider ret-roactivity of judicial ruling). The panel granted the stay request. Subsequently, the Arizona Supreme Court denied Sum-merlin’s motion to recall the mandate. This decision exhausted all of Summerlin’s potential state remedies. Cf. Woods v. Kemna, 13 F.3d 1244, 1245-46 (8th Cir.1994) (noting that habeas petitioners need not ordinarily resort to extraordinary state remedies, such as recall of the mandate, to satisfy federal exhaustion requirements, but holding that exhaustion might be required when there was a real possibility of relief under extraordinary and unique circumstances). After the Arizona Supreme Court denied Summerlin’s motion to recall the mandate, the panel requested a vote of our Court as to whether this case should be reheard en bane. Following an affirmative vote of a majority of the non-recused active members of the Court, see Summerlin v. Stewart, 310 F.3d 1221 (9th Cir.2002), the case was reheard en banc on December 10, 2002. We have jurisdiction pursuant to 28 U.S.C. § 2253. The Warden does not contend that Summerlin failed to exhaust his state remedies or that any of his claims are procedurally defaulted. Because this appeal was filed after the effective date of the Antiterrorism and Effective Death Penalty Act of 1996, Pub.L. No. 104-132, 110 Stat. 1214 (“AEDPA”), the right to appeal in this case is governed by AEDPA rules. See Slack v. McDaniel, 529 U.S. 473, 482, 120 S.Ct. 1595, 146 L.Ed.2d 542 (2000). However, because the petition for habeas corpus was filed before AEDPA’s effective date, pre-AEDPA law governs the petition itself. See Lindh v. Murphy, 521 U.S. 320, 327, 117 S.Ct. 2059, 138 L.Ed.2d 481 (1997). Summerlin argues on appeal that: 1. He did not receive effective assistance of counsel during the guilt phase of his trial in violation of his rights under the Sixth Amendment; 2. The Arizona death penalty statute, as applied to him, is unconstitutional in that it permits a judge rather than a jury to determine the elements necessary for a capital sentence; 3. He did not receive effective assistance of counsel during the sentencing phase of his capital trial in violation of his rights under the Sixth Amendment; 4. His court-appointed public defender had a conflict of interest that adversely affected her representation at a critical stage of the proceedings, in violation of his rights under the Sixth Amendment; 5. He was deprived of his right to due process of law because the trial judge was addicted to marijuana during his trial and deliberated over his sentence while under the influence of marijuana; and 6. Cumulative errors require reversal of his sentence and conviction. Summerlin’s only claim specific to the conviction phase alone is his argument that he received ineffective assistance of counsel during his guilt-phase trial. With the exception of his cumulative error contention, the remainder of Summerlin’s claims relate to the imposition of the death sentence. II Summerlin alleges that he was denied the effective assistance of counsel at the guilt phase of his murder trial in violation of the Sixth Amendment as interpreted in Strickland v. Washington, 466 U.S. 668, 104 S.Ct. 2052, 80 L.Ed.2d 674 (1984). We review the dismissal of a habeas petition de novo, including the mixed questions of law and fact raised by claims alleging ineffective assistance of counsel. See Williams v. Woodford, 306 F.3d 665, 684 (9th Cir.2002); Hendricks v. Calderon, 70 F.3d 1032, 1036 (9th Cir.1995). To prevail on this claim, Summerlin must demonstrate first that the performance of his counsel fell below an objective standard of reasonableness, and second that “there is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different.” Strickland, 466 U.S. at 694, 104 S.Ct. 2052. Failure to satisfy either prong of the Strickland test obviates the need to consider the other. See id. at 687, 104 S.Ct. 2052. We begin with the “strong presumption that counsel’s conduct falls within the wide range of reasonable professional assistance,” and with the acknowledgment that “[j]udicial scrutiny of counsel’s performance must be highly deferential.” Id. at 689, 104 S.Ct. 2052. However, defense counsel has “a duty to make reasonable investigations or to make a reasonable decision that makes particular investigations unnecessary.” Id. at 691, 104 S.Ct. 2052. “[Strategic choices made after less than complete investigation are reasonable precisely to the extent that reasonable professional judgments support the limitations on investigation.” Id. at 690-91, 104 S.Ct. 2052. Summerlin alleges that his trial lawyer failed to investigate and to present his “only viable defense,” namely, that Sum-merlin had an organic brain dysfunction and an “impaired ability to premeditate or to exercise self-control.” To analyze this issue properly, we must examine the mental defenses then available under Arizona law. At the time, Arizona had adopted the M’Naghten test “as the sole standard for criminal responsibility.” State v. Ramos, 133 Ariz. 4, 648 P.2d 119, 121 (1982) (internal quotation marks omitted). To sustain a defense of legal insanity: An accused must have had at the time of the commission of the criminal act: (1) Such a defect of reason as not to know the nature and quality of the act, or (2) If he did know, that he did not know he was doing what was wrong. State v. Christensen, 129 Ariz. 32, 628 P.2d 580, 583 (1981). At the time Summerlin was charged, Arizona already had rejected the affirmative defense of diminished capacity. See State v. Mott, 187 Ariz. 536, 931 P.2d 1046, 1051 (1997) (“Because the legislature has not provided for a diminished capacity defense, we have since consistently refused to allow psychiatric testimony to negate specific intent.”). Thus, the situation that confronted Klink was unlike that in Pirtle v. Morgan, 313 F.3d 1160, 1169-73 (9th Cir.2002) (holding that counsel had been constitutionally ineffective for not asserting a diminished capacity defense then available under Washington law). The Arizona Supreme Court also had held, as a matter of law, that criminal defendants could not present psychiatric testimony to negate the element of specific intent. State v. Laffoon, 125 Ariz. 484, 610 P.2d 1045, 1047 (1980). Arizona did allow the introduction of psychiatric evidence as to a defendant’s tendency to act on impulse as probative of an absence of premeditation. Christensen, 628 P.2d at 582-83. However, under Arizona law, the standard for establishing premeditation is not high. The prosecution only need show that the defendant “had time to reflect after forming the intent to kill.” Clabourne v.Lewis, 64 F.3d 1373, 1380 (9th Cir.1995) (citing State v. Neal, 143 Ariz. 93, 692 P.2d 272, 276 (1984)). “This length of time could have been as instantaneous as it takes to form successive thoughts in the mind, and premeditation may be proven by circumstantial evidence.” Neal, 692 P.2d at 276 (citing State v. Lacquey, 117 Ariz. 231, 571 P.2d 1027, 1030 (1977)). Thus, Summerlin’s trial counsel faced formidable legal hurdles in presenting a psychiatric defense at the guilt phase. Nonetheless, counsel conducted a substantial amount of investigation into a potential psychiatric defense. Summerlin’s first counsel moved for a mental examination under Ariz. R.Crim. P. 11 to determine whether Summerlin was competent to stand trial. Upon examination, Dr. Tu-chler concluded that Summerlin, although “functionally mentally retarded,” did not have a mental disease or defect. Before she withdrew from the case, Roe thoroughly investigated Dr. Garcia-Bunuel’s suspicion of psychomotor epilepsy. She obtained neurological testing and pursued this possible diagnosis with Dr. Bendheim, as revealed in the following letter the doctor sent to Judge Derickson in December 1981: We again discussed the possibility of psychomotor epilepsy, especially in view of Dr. Garcia Bunuel’s findings that this man had very vivid olfactory (smell) hallucinations preceding outbursts. I went over this whole situation again and told Miss [Roe] that the neurologists have been unable to find psychomotor epilepsy, although there was some slowing of the wave patterns in the temporal lobes, where psychomotor epileptic attacks usually originate. While a positive electroencephalogram, which was not obtained here, would make a positive diagnosis, an essentially negative EEG does not entirely rule out the possibility of epileptic-type seizures, and for this reason I see absolutely no harm and potentially quite a bit of benefit to place this defendant on anti-epileptic, anti-seizure type medication, even though the diagnosis has not been established. During post-conviction hearings, Roe testified that she met with trial counsel Klink on two or three occasions and spent a number of hours discussing her investigative efforts and the viability of a possible insanity defense. She stated that she discussed this aspect of the case with Klink “at great length,” explaining to Klink the examinations and conclusions of all of the examining doctors. Klink testified that, after consulting with Roe, he made a tactical decision not to pursue an insanity defense due to the lack of evidence. Klink did not follow up on Dr. Garcia Bunuel’s earlier suspicion of psychomotor epilepsy because the doctor had changed his opinion and was out of the country at the time of trial. Instead, Klink made a decision to defend his client by arguing that the facts and circumstances of the prosecution’s case did not support a verdict of first-degree murder. Summerlin himself desired this fact-based defense. In assessing an attorney’s performance, a reviewing court must make every effort “to eliminate the distorting effects of hindsight, to reconstruct the circumstances of counsel’s challenged conduct, and to evaluate the conduct from counsel’s perspective at the time.” Strickland, 466 U.S. at 689, 104 S.Ct. 2062. As the Supreme Court recently reiterated, this evaluation must include “an objective review of [counsel’s ] performance, measured for ‘reasonableness under prevailing professional norms,’ which includes a context-dependent consideration of the challenged conduct.” Wiggins v. Smith, — U.S. -, 123 S.Ct. 2627, 2536, 156 L.Ed.2d 471 (2003) (quoting Strickland, 466 U.S. at 688, 104 S.Ct. 2052). A review of the record indicates that Klink’s trial performance did not fall below the objective standard of reasonableness required under Strickland. In deciding whether to pursue evidence of Summerlin’s mental state, Klink was entitled to rely on the opinions of the mental health experts who already had examined Summerlin. See Hendricks, 70 F.3d at 1038. At the time, none of the doctors would opine that Summerlin was suffering from a mental disease or defect that would provide a foundation for an insanity defense. None of the physicians, including Dr. Garcia Buñuel, was able to diagnose Summerlin as clearly suffering from psy-chomotor epilepsy. It thus was reasonable for Klink not to investigate this possibility further. Cf. Wiggins, — U.S. at - -, 123 S.Ct. at 2536-38 (upholding an ineffective assistance claim against counsel who curtailed investigation despite promising leads in preliminary discovery). Likewise, given the doctors’ inability to make a diagnosis, Klink’s tactical decision to forgo presenting what little evidence he had of epilepsy was certainly within the “wide range of professionally competent assistance.” Strickland, 466 U.S. at 690, 104 S.Ct. 2052; see also Harris v. Vasquez, 949 F.2d 1497, 1525 (9th Cir.1990) (“It is also acceptable trial strategy to choose not to call psychiatrists to testify when they can be subjected to cross-examination based on equally persuasive psychiatric opinions that reach a different conclusion.”). Psychiatric testimony would have been admissible concerning Summerlin’s impulsive personality to show absence of premeditation. See Vickers v. Ricketts, 798 F.2d 369, 372-73 (9th Cir.1986). However, under the circumstances of the case, Summerlin has not shown that he was prejudiced by the failure to introduce such testimony. The basis of the State’s premeditation theory was not that Summerlin had planned the crime; rather, it was that he formed the required premeditation during the commission of the crime. To prove its point, the State relied on the circumstances surrounding the crime, including the fact that sexual assault occurred prior to the murder and the fact that Summerlin had retrieved a blunt object after the assault to commit the murder. The State also relied on the uncontro-verted evidence as to how the murder was committed, specifically that Bailey had been hit repeatedly and forcefully on each side of her head. As the Supreme Court of Arizona later noted, Summerlin’s “excessive and purposeful actions demonstrate more than just a ‘reactionary’ homicide.” State v. Summerlin, 675 P.2d at 694. The State underscored this theory with presentation of graphic photographic evidence of the numerous wounds sustained by Bailey. The State’s witness testified that any one of the blows to the victim’s head was sufficient to kill the victim, yet numerous, deep lacerations were evident from the photographs. Klink was not questioned during the post-conviction hearings about his choice not to present psychiatric evidence of impulsiveness, so we do not know whether this decision was strategic. However, after carefully reviewing the record, the district court concluded that there is no reasonable probability the jury would have acquitted Summerlin of first-degree murder had Klink introduced evidence of Summerlin’s impulsive personality. The district court therefore concluded that Summerlin could not establish Strickland prejudice as to this claim. See 466 U.S. at 691, 104 S.Ct. 2052 (“An error by counsel, even if professionally unreasonable, does not warrant setting aside the judgment of a criminal proceeding if the error had no effect on the judgment.”). The district court’s assessment was correct. The psychiatric testimony on this point would have been limited to a general description of Summerlin’s behavioral tendencies. Given the State’s theory, this would have had only marginal probative value in determining whether Summerlin formed premeditation during the commission of the offense. The jury was instructed properly on the State’s premeditation theory, which was a correct statement of Arizona law. In this context, and considering the “totality of the evidence,” additional psychiatric testimony would not have generated a “reasonable probability that at least one juror would have struck a different balance.” Wiggins, — U.S. at -, 123 S.Ct. at 2543. Thus, Summerlin has not established a “probability sufficient to undermine confidence in the outcome” of the guilt phase of his trial. Strickland, 466 U.S. at 694, 104 S.Ct. 2052. Ill The first penalty-phase question presented to us is whether the Arizona death penalty statute, as applied to Summerlin, is unconstitutional in that it permits a judge rather than a jury to determine the elements necessary for a death sentence. The Supreme Court recently has held that Arizona’s capital sentencing scheme was incompatible with the Sixth Amendment right to a trial by jury “to the extent that it allow[ed] a sentencing judge, sitting without a jury, to find an aggravating circumstance necessary for imposition of the death penalty.” Ring, 536 U.S. at 609, 122 S.Ct. 2428. The Supreme Court did not decide whether the holding in Ring applied to petitioners, such as Summerlin, who raised the constitutional challenge in collateral post-conviction proceedings rather than on direct appeal. Because the Warden has argued that Teague v. Lane, 489 U.S. 288, 109 S.Ct. 1060, 103 L.Ed.2d 334 (1989), bars relief on this issue, we must decide whether Ring has retroactive application to cases on federal habeas review. Horn v. Banks, 536 U.S. 266, 272, 122 S.Ct. 2147, 153 L.Ed.2d 301 (2002) (holding that the court of appeals erred by not performing a Teague analysis when the issue was “properly raised by the state”) (citing Caspari v. Bohlen, 510 U.S. 383, 389, 114 S.Ct. 948, 127 L.Ed.2d 236 (1994) (“[I]f the State does argue that the defendant seeks the benefit of a new rule of constitutional law, the court must apply Teague before considering the merits of the claim”) (emphasis in original)). In short, now that the Supreme Court has decided that Timothy Ring’s capital murder conviction must be vacated because the judge was constitutionally disqualified from deciding whether Ring was eligible for the death penalty, the question is whether others who received the same constitutionally infirm sentence, including those who previously raised the identical issue, are eligible for the same relief or whether they should remain subject to execution. The question of whether a newly announced constitutional rule will apply retroactively on collateral review is a relatively recent inquiry in American jurisprudence. As Justice Holmes observed at the turn of the century, “[¿judicial decisions have had retrospective operation for near a thousand years.” Kuhn v. Fairmont Coal Co., 215 U.S. 349, 372, 30 S.Ct. 140, 54 L.Ed. 228 (1910) (Holmes, J., dissenting). At common law, the ret-roactivity question never arose because judges were believed to be discovering rules rather than declaring them. John C. Gray, The Nature and Sources of the Law 222 (1st ed.1909). Even now, a presumption exists that “a court is to apply the law in effect at the time it renders its decision, unless doing so would result in manifest injustice or there is statutory direction or legislative history to the contrary.” Bradley v. Sch. Bd. of Richmond, 416 U.S. 696, 711, 94 S.Ct. 2006, 40 L.Ed.2d 476 (1974). As the Supreme Court noted, “ ‘[Bjoth the common law and our own decisions’ have ‘recognized a general rule of retrospective effect for the constitutional decisions of this Court.’ ” Harper v. Va. Dep’t of Taxation, 509 U.S. 86, 94, 113 S.Ct. 2510, 125 L.Ed.2d 74 (1993) (quoting Robinson v. Neil, 409 U.S. 505, 507, 93 S.Ct. 876, 35 L.Ed.2d 29 (1973)). Following the Civil War and enactment of the Fourteenth Amendment, Congress expanded the scope of habeas corpus review to cover challenges brought by those in state custody, see Act of 1867, ch. 28, § 1, 14 Stat. 385 (codified as amended at 28 U.S.C. § 2241(c)(3)), prompting the Supreme Court to determine the proper scope of federal habeas jurisdiction. By 1953, the Supreme Court confirmed the cognizability of all federal constitutional claims filed by state prisoners. Brown v. Allen, 344 U.S. 443, 73 S.Ct. 397, 97 L.Ed. 469 (1953). The expanding scope of federal review, coupled with a significant increase in the filing of federal habeas petitions by state prisoners, provided the Supreme Court with the opportunity to review for the first time a number of alleged constitutional deprivations. Walter V. Schaefer, Federalism and State Criminal Procedure, 70 Harv. L.Rev. 1, 21-22 (1956). Epochal constitutional criminal procedural protections were announced, and in their wake, a novel discussion arose as to whether a new constitutional rule of criminal procedure should be applied retroactively on direct or collateral review. This debate, a “product of the Court’s disquietude with the impacts of its fast-moving pace of constitutional innovation in the criminal field,” Mackey v. United States, 401 U.S. 667, 676, 91 S.Ct. 1160, 28 L.Ed.2d 404 (1971) (Harlan, J., concurring in part and dissenting in part), culminated in Linkletter v. Walker, 381 U.S. 618, 85 S.Ct. 1731, 14 L.Ed.2d 601 (1965). In Linkletter, a defendant was convicted based on evidence that was obtained during a warrantless search. A year after the defendant had exhausted his state appeals, the Supreme Court decided Mapp v. Ohio, 367 U.S. 643, 81 S.Ct. 1684, 6 L.Ed.2d 1081 (1961). Subsequently, the defendant filed a habeas petition arguing that Mapp required reversal of his conviction. The Supreme Court held that even though “the Constitution neither prohibits nor requires retrospective effect,” Linkletter, 381 U.S. at 629, 85 S.Ct. 1731, a constitutional rule of criminal procedure would not be retroactive unless, under a case-by-case analysis, three factors — the purpose of the new rule, reliance on prior doctrine, and the effect of retroactivity on the administration of justice — favor retroactive application of the rule. Id. at 636, 85 S.Ct. 1731. The Linkletter rule applied to convictions pending on direct review as well as to final convictions challenged collaterally by a federal habeas petition. Johnson v. New Jersey, 384 U.S. 719, 732, 86 S.Ct. 1772, 16 L.Ed.2d 882 (1966). The tripartite Linkletter test proved difficult to apply. Justice Harlan observed that it had fostered the creation of “an extraordinary collection of rules to govern the application of that principle.” Desist v. United States, 394 U.S. 244, 256-57, 89 S.Ct. 1030, 22 L.Ed.2d 248 (1969) (Harlan, J., dissenting). He contended that the test produced inconsistent results, leading to different treatment for similarly-situated defendants. See id. Justice Harlan remained critical of the Linkletter test throughout a series of subsequent cases. See, e.g., Mackey, 401 U.S. at 675, 91 S.Ct. 1160 (Harlan, J., concurring in part and dissenting in part); Coleman v. Alabama, 399 U.S. 1, 19, 90 S.Ct. 1999, 26 L.Ed.2d 387 (1970) (Harlan, J., concurring in part and dissenting in part); Von Cleef v. New Jersey, 395 U.S. 814, 817, 89 S.Ct. 2051, 23 L.Ed.2d 728 (1969) (Harlan, J., concurring in result); Jenkins v. Delaware, 395 U.S. 213, 222, 89 S.Ct. 1677, 23 L.Ed.2d 253 (1969) (Harlan, J., dissenting); Desist, 394 U.S. at 256, 89 S.Ct. 1030 (Harlan, J., dissenting). He argued instead that new constitutional rules ought to apply to all cases that were not final or that were pending on direct review. Mackey, 401 U.S. at 678-80, 91 S.Ct. 1160. He also contended that new procedural (as opposed to substantive) due process rules ought not to apply retroactively on habeas review unless the claim implicated procedures “implicit in the concept of ordered liberty” or addressed rules that “alter our understanding of the bedrock procedural elements that must be found to vitiate the fairness of a particular conviction.” Id. at 693-94, 91 S.Ct. 1160 (internal quotation marks and citations omitted). The analytical framework propounded by Justice Harlan ultimately proved persuasive. In Griffith v. Kentucky, 479 U.S. 314, 107 S.Ct. 708, 93 L.Ed.2d 649 (1987), the Supreme Court adopted the first portion of Justice Harlan’s analysis, noting that “[i]n Justice Harlan’s view, and now in ours, failure to apply a newly declared constitutional rule to criminal cases pending on direct review violates basic norms of constitutional adjudication.” Id. at 322, 107 S.Ct. 708. The Court therefore held that “a new rule for the conduct of criminal prosecutions is to be applied retroactively to all cases, state or federal, pending on direct review or not yet final.” Id. at 328, 107 S.Ct. 708. Two years later, the Court clarified its retroactivity jurisprudence in the habeas context in Teague. Importing Justice Harlan’s analysis, Teague held that “[u]n-less they fall within an exception to the general rule, new constitutional rules of criminal procedure will not be applicable to those cases which have become final before the new rules are announced.” 489 U.S. at 310, 109 S.Ct. 1060. Teague also adopted Justice Harlan’s two exceptions, providing that a new rule of criminal procedure would be retroactive if it “place[d] certain kinds of primary, private individual conduct beyond the criminal law-making authority to proscribe,” or if the rule “require[d] the observance of those procedures that ... are implicit in the concept of ordered liberty.” Id. at 311, 109 S.Ct. 1060 (internal quotation marks omitted). The Supreme Court explained that the second exception had two components, formulated by combining aspects from Justice Harlan’s dissents in Desist and Mackey. The Court thus limited the exception for “watershed rules of criminal procedure” to those procedures that both “alter our understanding of the bedrock procedural elements that must be found to vitiate the fairness of a particular conviction,” id. (quoting Mackey, 401 U.S. at 693, 91 S.Ct. 1160) (internal quotation marks omitted; emphasis added in Teag-ue ), and “without which the likelihood of an accurate conviction is seriously diminished.” Id. at 313, 109 S.Ct. 1060. Before applying these concepts to the instant case, it is important to set the appropriate analytic framework. The threshold question in a Teague analysis is whether the rule the petitioner seeks to apply is a substantive rule or a procedural rule, because “Teague by its terms only applies to procedural rules.” Bousley v. United States, 523 U.S. 614, 620, 118 S.Ct. 1604, 140 L.Ed.2d 828 (1998). If the rule is procedural, the court then conducts a three-step analysis to determine whether Teague bars its application. See O’Dell v. Netherlands 521 U.S. 151, 156-57, 117 S.Ct. 1969, 138 L.Ed.2d 351 (1997). First, the reviewing court “must ascertain the date on which the defendant’s conviction and sentence became final for Teague purposes.” Caspari, 510 U.S. at 390, 114 S.Ct. 948. Second, the court must survey “the legal landscape as it then existed,” Graham v. Collins, 506 U.S. 461, 468, 113 S.Ct. 892, 122 L.Ed.2d 260 (1993), to determine whether existing precedent compelled a finding that the rule at issue “was required by the Constitution.” Lambrix v. Singletary, 520 U.S. 518, 527, 117 S.Ct. 1517, 137 L.Ed.2d 771 (1997) (internal quotation marks and citations omitted). If existing precedent already required application of the rule, the Teague bar does not apply. If, by contrast, the procedure at issue is considered a new rule for Teague purposes, the court must proceed to the third step and determine whether either of the two announced exceptions applies. Teague, 489 U.S. at 307, 109 S.Ct. 1060 (plurality). The presumption against ret-roactivity is overcome only if the new rule prohibits “a certain category of punishment for a class of defendants because of their status or offense,” Penry v. Lynaugh, 492 U.S. 302, 330, 109 S.Ct. 2934, 106 L.Ed.2d 256 (1989), abrogated on other grounds by Atkins v. Virginia, 536 U.S. 304, 122 S.Ct. 2242, 153 L.Ed.2d 335 (2002), or presents a new “watershed rule of criminal procedure” that enhances accuracy and alters our understanding of bedrock procedural elements essential to the fairness of a particular conviction. Teague, 489 U.S. at 311, 109 S.Ct. 1060 (plurality; citations omitted). IV We first consider the threshold Teague question, namely whether Ring announced a substantive rule or a procedural rule. See Bousley, 523 U.S. at 620, 118 S.Ct. 1604. Unlike strictly procedural rules, “new rules of substantive criminal law are presumptively retroactive.” See, e.g., Santana-Madera v. United States, 260 F.3d 133, 138 (2d Cir.2001) (citing United States v. Mandanici, 205 F.3d 519, 525 (2d Cir.2000)), cert. denied, 534 U.S. 1083, 122 S.Ct. 817, 151 L.Ed.2d 701 (2002). Thus, the Teague retroactivity bar does not apply if the rule Ring announced is substantive, rather than procedural, in nature. Bousley, 523 U.S. at 620, 118 S.Ct. 1604. As Erie doctrine demonstrates in the context of civil litigation, the distinction between “substantive” and “procedural” is not always easy to divine. Erie R.R. Co. v. Tompkins, 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188 (1938); see also Hanna v. Plu- mer, 380 U.S. 460, 471-74, 85 S.Ct. 1136, 14 L.Ed.2d 8 (1965); Guar. Trust Co. of N.Y. v. York, 326 U.S. 99, 109, 65 S.Ct. 1464, 89 L.Ed. 2079 (1945). The Supreme Court acknowledged this problem in a pre-Teague consideration of the difference between substantive and procedural criminal law, noting that “[w]e would not suggest that the distinction that we draw is an ironclad one that will invariably result in the easy classification of cases in one category or the other.” Robinson, 409 U.S. at 509, 93 S.Ct. 876. However difficult it is to locate, though, “[t]his distinction between substance and procedure is an important one in the habeas context.” Bousley, 523 U.S. at 620, 118 S.Ct. 1604. In giving shape to this important distinction, the Supreme Court has understood decisions of “criminal procedure” to be those decisions that implicate how the criminal trial process functions. Under Teague, only those decisions of “procedure” that insert into the criminal trial process a mechanism “ ‘without [which] the likelihood of an accurate conviction is seriously diminished’” apply retroactively. Id. (quoting Teague, 489 U.S. at 313, 109 S.Ct. 1060). Decisions of “substantive criminal law,” by contrast, are those that reach beyond issues of procedural function and address the meaning, scope, and application of substantive criminal statutes. Id. (noting that a Supreme Court holding is “substantive” for Teague purposes when it impacts the scope and application of a “substantive federal criminal statute”); see also Davis v. United States, 417 U.S. 333, 346, 94 S.Ct. 2298, 41 L.Ed.2d 109 (1974) (including within the definition of “substantive” those decisions that remove primary conduct from the purview of criminal punishment). Thus, for Teague purposes, a new rule is one of “procedure” if it impacts the operation of the criminal trial process, and a new rule is one of “substance” if it alters the scope or modifies the applicability of a substantive criminal statute. Bousley, 523 U.S. at 620, 118 S.Ct. 1604. In Bousley, the Supreme Court applied this substantive procedural logic, rejecting the government’s Teague-based non-retro-activity argument because the case called for a construction of a federal statute. Teague, Chief Justice Rehnquist explained, “is inapplicable to the situation in which this Court decides the meaning of a criminal statute enacted by Congress.” Id. For the same reason, we recently determined that the rule announced in Richardson v. United States, 526 U.S. 813, 815, 119 S.Ct. 1707, 143 L.Ed.2d 985 (1999), requiring jury unanimity on individual violations alleged as part of a continuing criminal enterprise, is substantive, not procedural, under Teague. See United States v. Montalvo, 331 F.3d 1052 (9th Cir.2003). All of our sister circuits that have considered the question agree with this categorization. “[Significant” to both this court’s and our sister circuits’ understanding of Richardson’s rule as substantive is the fact that Richardson “was ‘deciding ] the meaning of a criminal statute.’ ” Montalvo, 331 F.3d at 1056 (citation omitted; alteration in original); see also Murr, 200 F.3d at 906. Explaining or redefining elements of an offense, we observed in Montalvo, constitutes a decision of substantive criminal law for Teague purposes. 331 F.3d at 1055-56; see also United States v. Dashney, 52 F.3d 298, 299 (10th Cir.1995). Thus, because Richardson expressly “analyz[ed] what constitutes ‘elements’ as opposed to brute facts or ‘means’ ” of an offense, the rule Richardson announced was substantive for Teague purposes. Montalvo, 331 F.3d at 1056. In the habeas context in particular, as Chief Judge Becker has observed, there are those cases that do “not fall neatly under either the substantive or procedural doctrinal category.” United States v. Woods, 986 F.2d 669, 677 (3d Cir.1993). In such cases, “the best approach is to recognize that [the case at issue] is neither entirely substantive nor procedural.” Id. at 678. Ring is such a decision. In one sense, Ring — like Apprendi — announced a procedural rule: Ring mandated that a jury, rather than a judge, must find aggravating circumstances in a capital case. Ring’s holding thus addressed, at least in part, the procedure by which any capital trial must be conducted. See Cannon v. Mullin, 297 F.3d 989, 994 (10th Cir.2002) (assessing the operation of Ring on Oklahoma law). In the context of substantive Arizona criminal law, however, Ring did more than answer a strictly procedural question. Thus, Ring is unlike Apprendi, in which the Supreme Court expressly declared that its decision had no impact on substantive criminal law, noting that “[t]he substantive basis for New Jersey’s enhancement is not at issue.” 530 U.S. at 475, 120 S.Ct. 2348. By important contrast, the substantive basis for Arizona’s capital sentencing scheme was precisely at issue in Ring. Ring rendered Arizona’s substantive capital murder statute unconstitutional. More than a procedural holding, Ring effected a redefinition of Arizona capital murder law, restoring, as a matter of substantive law, an earlier Arizona legal paradigm in which murder and capital murder are separate substantive offenses with different essential elements and different forms of potential punishment. That is, as applied to the particular Arizona murder statute at issue here, Ring’s holding was “substantive” for Teague purposes. See Bousley, 523 U.S. at 620, 118 S.Ct. 1604 (noting that a Supreme Court holding is “substantive” when it impacts the scope and application of a “substantive federal criminal statute”). A careful analysis of the structure and history of the relevant Arizona statutes, coupled with a close examination of the underlying rationale of Ring and the Supreme Court’s related jurisprudence, reveals that Ring is, as to Arizona, a “substantive” decision, even if its form is partially procedural. In 1901, the Territory of Arizona enacted its first death penalty statute, leaving capital sentencing to the discretion of the jury except where the defendant entered a plea of guilty. See Ariz. Territorial Rev. Stat., tit. 8, § 174 (1901). In relevant part, the 1901 Arizona statute provided that [e]very person guilty of murder in the first degree shall suffer death or i