OPINION

Brett Patrick Pensinger was convicted of kidnapping and first-degree murder and sentenced to death in 1982. After his California state appeals, Pensinger filed a writ of habeas corpus in federal court prior to the enactment of the Anti-Terrorism and Effective Death Penalty Act of 1996 (“AEDPA”), Pub.L. No. 104-132, 110 Stat. 1214. The district court granted in part and denied in part Pensinger’s federal ha-beas petition, ultimately vacating the kidnap-murder special circumstance and the death sentence. Both parties appealed. “[B]eeause in most matters it is more important that the applicable rule of law be settled than that it be settled right,” we agree with the district court, and uphold Pensinger’s conviction for the kidnappings and murder but overturn his sentence of death. Burnet v. Coronado Oil & Gas Co., 285 U.S. 393, 406 , 52 S.Ct. 443 , 76 L.Ed. 815 (1932) (Brandeis, J., dissenting).

We reject the State’s request that we invoke our discretion to sua sponte apply the non-retroactivity bar under Teague v. Lane, 489 U.S. 288 , 109 S.Ct. 1060 , 103 L.Ed.2d 334 (1989), which ordinarily prevents a federal court from granting habeas relief to a state prisoner based on a rule announced after his conviction and sentence became final, to bar Pensinger’s instructional error claim. We reject the State’s challenge to the district court’s holding that the trial court violated Pen-singer’s constitutional rights by failing to instruct the jury sua sponte in accordance with People v. Green, 27 Cal.3d 1 , 164 Cal.Rptr. 1 , 609 P.2d 468 (1980). Green held that a kidnap-murder special circumstance requires proof that the kidnapping was committed for an independent felonious purpose (i.e., not merely incidental to the murder). We also reject Pensinger’s ineffective assistance of counsel claim based on his trial counsel’s failure to request a Green instruction. We have jurisdiction under 28 U.S.C. §§ 1291 and 2253, and we affirm the grant of partial habeas relief.

I

A

On August 4, 1981, 19-year-old Brett Pensinger met Vickie and Michael Melan-der, Sr., at the Silver Saddle Bar in Parker, Arizona, near the Colorado River separating Arizona from California. Pen-singer drank and played pool with the Melanders, who had been drinking there since noon. At about 7 p.m., Pensinger drove Vickie to a friend’s home where she picked up her two children, five-year-old Michael, Jr., and five-month-old Michele. The four drove off in Pensinger’s pickup truck around 7:40 p.m. toward the Turtle Barn Bar in Parker. Vickie and Pensinger went in for another drink, leaving the children unattended in the truck. While they were inside, Michael, Jr., found Pen-singer’s rifle inside his truck and pointed it at a passerby in the Turtle Barn parking lot, who confiscated it. When Vickie came out to check on the children, Michael, Jr., told her that a man had stolen Pensinger’s gun.

Vickie testified that when she told Pen-singer about the missing rifle he became so angry that she ran off down the street. Nonetheless, the four subsequently drove to the Silver Saddle, where Vickie again left the children unattended in the truck. She reported to her husband that she and Pensinger were going to the Yuma County Sheriffs substation to report the theft of the rifle. Vickie and Pensinger, still with the children in the truck, arrived at the sheriffs substation about 8:20 p.m. Vickie went into the station, expecting Pensinger to follow. While Vickie reported the theft, she looked out and noticed that the truck was gone, but assumed that Pensinger was either looking for his gun or was back at the Silver Saddle. Around 9 p.m., a Parker City police officer drove Vickie back to the Silver Saddle. Ten minutes after arriving Vickie realized that her children were still unaccounted for and called the police.

A customer and an employee of the P.D.Q. Market in Parker testified that a tall young man wearing a cowboy hat came into the store sometime between 8:45 and 9 p.m. on August 4th. Both witnesses said he was looking for someone who had stolen a rifle out of his truck while his wife and five-year-old child were in it. He was reported to be beside himself with rage, and said that if the person who stole the gun came in and tried to use it in a robbery of the store, the store clerk had permission to use the gun to “blow their heads off.” The store employee saw the man get into a light-colored pickup and drive off. The witness did not see anyone else in the truck.

Michael, Jr., confirmed his mother’s testimony at trial. He further testified that he did not recall stopping at the P.D.Q. Market, but that after leaving the sheriffs substation and driving on a road outside of town Pensinger told him a cop was following him and that Michael, Jr., should get out and wait until Pensinger came back. Pensinger never returned. Later that night at about 9:30 p.m., a couple picked up Michael, Jr., as he hitchhiked on the roadside near the Parker Dam on the California side.of the river. They called the Yuma' County Sheriff, and waited to meet the deputy in a restaurant.

Michele’s body was discovered six days later on August 10, 1981, in the Black Meadows Landing Dump in San Bernardi-no County, California, some nine miles from where Michael, Jr., was picked up. The baby girl victim had many disfiguring injuries, including a crushing blow to the skull that occurred before death. Michele’s body was partially decomposed. She had a long diagonal incision from below the rib cage to above her pubic region, and an egg-shaped cut between the legs encompassing the location of the vagina, anus, and surrounding supportive tissue. The uterus was also missing, likely removed with ¿nother long incision below the rib cage. The pathologist who conducted the autopsy was unable to determine whether the incisions were made before or after death, or whether Michele had been sexually assaulted because of the missing vagina. Forensic examination revealed no evidence of semen on the remaining parts of the body.

B

Pensinger was arrested in Midland, Texas, in mid-August 1981 and charged with kidnapping Michele and Michael, Jr., and murdering Michele. Although investigators found a box of blades for a utility knife in the truck, all tests for blood, hair, and fibers were negative. It could not be determined whether a stain on the left front fender of the pickup was human or animal blood. When the police arrested Pensinger, he had bloodstains on his pants, shirt, belt, and boots, but the stains were not compared to the victim’s blood in time for the trial.

During Pensinger’s pre-trial confinement, more evidence of Michele’s murder came to light. When Pensinger was extradited from Texas to Oregon to face unrelated charges there, he was housed in the Washington County Jail with Tony Kross-man. Krossman testified that Pensinger told him that he was trying to make bail because he was afraid that warrants would arrive from Arizona and California charging him with kidnapping and murder. Pensinger told Krossman that he had killed someone. The only details Kross-man could remember were that Pensinger said the crime happened in Parker or Flagstaff, Arizona, and that he was afraid a blonde woman had seen him in the course of the crime.

After Pensinger was transferred to the San Bernardino County Jail in September 1981, he was housed in an isolation unit next to inmate Gary Howard. Howard provided a much more detailed statement attributed to Pensinger. Howard testified that Pensinger told him he had picked up a. baby in Arizona and killed her. He drove out of town, and when the little girl started crying, he slapped her hard enough to break her ribs, but she did not stop crying. In one conversation Pensinger said that when he stopped to relieve himself, Michael, Jr., ran off. In another conversation Pensinger said that Michael, Jr., was still in the car when he stopped and tried to force the baby to orally copulate him. Howard also stated Pensinger told him that he attempted to have sex with Michele. When he could not do this, he cut her belly and private parts out. He then drove to a dump, put her in a plastic bag, and threw her out. He said he cut the baby with a hunting knife and left her body near Parker Dam. In another conversation Pensinger said that he had removed the sex organs to hide the sexual assault and to make it difficult to identify the baby’s sex.

David Hicks, another jailhouse informant, testified that in October 1981, Pen-singer asked Hicks if he would kill Howard for $500 because Howard was testifying against Pensinger. Hicks further recounted that Pensinger told him he had been drinking with the Melanders on the day of the crime. After Vickie went into the sheriffs station to report a stolen rifle, Pensinger said he drove off because he was frightened about being in the truck, which Pensinger had stolen from an uncle, and he feared he had outstanding warrants for his arrest from Oregon. He stopped in the desert to urinate and the boy ran off. He drove to a junkyard and “did in” the baby girl. He tried to have sex with her but she was too small so he cut her. He put her in a plastic bag and threw her body in the junkyard. Pensinger told Hicks that he went to the dam and buried the knife. He told Hicks he had not thrown the knife into the water, as he had told Howard. Hicks told officers about the location where Pensinger said he had put the knife. Officers later recovered a utility knife handle from that location in plain sight' on a pile of rocks. It was too weathered to yield any forensic clues.

At trial, all three jailhouse informants denied receiving any benefit for their testimony, but Howard and Hicks were substantially discredited during cross-examination. The investigating officers in the case confirmed that they had offered Krossman, Howard, and Hicks no benefits for their testimony.

Pensinger attempted to show at trial that someone else murdered Michele. The defense case consisted of attacks on the jailhouse informants and Vickie Melander. Pensinger took the stand and testified that after driving Vickie to pick up her children, and stopping at the Turtle Barn Bar, Michael, Jr., informed them of the stolen rifle. He denied becoming enraged or that Vickie ever ran from him. Pensinger stated that he then drove back to the Silver Saddle to see if Vickie’s husband would help look for the missing weapon. Vickie asked Pensinger to take her to another bar, the name of which he did not recall, so she could arrange a place to stay for the night.

Pensinger insisted that he dropped Vickie and the children off at the bar, subsequently purchased gas, and stopped and inquired about his rifle at the P.D.Q. Market. He admitted to having been upset and telling store employees that if they had trouble with whoever took the gun, to blow their head off. He then went into a restaurant and talked to a deputy sheriff he saw there, who advised Pensinger to report the loss to the local police. After an unsuccessful search for his rifle, Pen-singer drove to Texas. He denied making any confessions to the three jailhouse informants.

At closing, the State argued that when Pensinger left the sheriffs substation, he did not have in mind kidnapping the children or murdering Michele. The prosecutor contended that Pensinger’s sole intention at that point was to look for the rifle. It was only after talking to the store clerk that Pensinger “finally decided he’s going to take matters into his own hands and strike back. And that’s the point where he kidnaps Michael and Michele.” The prosecutor did not specify how Pensinger intended to strike back. However, as to the sexual offense charges, the prosecutor argued that he:

Neither the defense nor the prosecution’s theory of the case turned on whether Michele’s murder advanced the independent felonious intent of kidnapping.

On August 3, 1982, a California jury convicted Pensinger of two counts of kidnapping and one count of first-degree murder. The jury also found true two special circumstances making Pensinger death-eligible: (1) murder committed in the course of a kidnapping, and (2) murder with the intent to torture the victim. The jury, however, rejected two other special circumstances: (1) murder in the commission of a lewd act on a child under the age of 14, and (2) murder committed in the course of oral copulation in violation of California Penal Code § 288a.

At issue here are the kidnap-murder special circumstance jury instructions. The trial court instructed the jury using California Criminal Jury Instruction (CALJIC) No. 8.81.17 .

The trial court did not include, nor did Pensinger’s trial counsel request, paragraph 2 of section 8.81.17 of the CALJIC, which codifies the California Supreme Court’s ruling in People v. Green, requiring an independent felonious purpose. The second paragraph of the jury instruction reads as follows:

CALJIC No. 8.81.17(2). Without the benefit of paragraph 2, the jury found true the kidnap-murder special circumstance and subsequently sentenced Pensinger to death.

C

Pensinger filed his opening brief on direct appeal on April 8, 1985. He filed his first state habeas petition on June 3, 1985. Five years later, in an opinion deciding the direct appeal and habeas petition, the California Supreme Court affirmed Pensinger’s convictions, the kidnap-murder special circumstance finding, and the penalty determination. People v. Pensinger, 52 Cal.3d 1210, 1229, 1257 , 278 Cal.Rptr. 640 , 805 P.2d 899 (1991). However, it reversed Pensinger’s torture-murder special circumstance because the jury was not instructed that the special circumstance required proof of intent to inflict torture. Id. at 1254-55 , 278 Cal.Rptr. 640 , 805 P.2d 899 . The court otherwise denied relief on the habeas petition. Id. at 1282 , 278 Cal.Rptr. 640 , 805 P.2d 899 . On October 21, 1991, the U.S. Supreme Court denied Pensinger’s petition for a writ of certiorari. Pensinger v. California, 502 U.S. 930 , 112 S.Ct. 351 , 116 L.Ed.2d 290 (1991).

D

Pensinger initiated his federal habeas proceedings on July 13, 1994. The district court stayed the proceedings pending Pen-singer’s filing of his state habeas corpus petition to exhaust certain claims. On July 26, 2000, the California Supreme Court denied Pensinger’s state habeas petitions on the unexhausted claims.

The district court then lifted the stay of the federal proceedings, and Pensinger filed an amended petition on October 2, 2000. Ultimately, the district court issued an order granting in part and denying in part Pensinger’s habeas petition. Pensinger v. Chappell, No. CV-92-1928-DSF (C.D.Cal. Nov. 30, 2012). The district court denied twenty-four claims, dismissed as moot an additional thirty-five, but granted relief on one claim. On that claim (Claim 24), it held that the superior court violated Pensinger’s constitutional rights by failing to instruct the jury sua sponte in compliance with People v. Green, that a kidnap-murder special circumstance requires proof that the kidnapping was committed for an independent felonious purpose (i.e., not merely incidental to the murder). As a result, the district court vacated the kidnap-murder special circumstance and the death sentence. The district court granted a limited certificate of appealability with respect to one subclaim (Claim 12(BB)) on whether Pensinger’s trial counsel was ineffective in failing to request a jury instruction in accordance with People v. Green. The district court denied a certificate of appealability for twenty-six other claims.

Pensinger appeals the district court’s ruling on Claim 12(BB) and requests that the panel expand the certificate of appeala-bility to include a multitude of other claims. The State filed a cross-appeal challenging the grant of relief under Claim 24.

II

We review denials of habeas petitions de novo. Rhoades v. Henry, 598 F.3d 495, 500 (9th Cir.2010). AEDPA does not apply here because Pensinger’s original federal petition, filed in 1994, preceded AEDPA’s enactment. See Woodford v. Garceau, 538 U.S. 202, 210 , 123 S.Ct. 1398 , 155 L.Ed.2d 363 (2003) (holding that AEDPA’s application depends on whether the petitioner filed an application for habeas relief seeking an adjudication on the merits after AEDPA’s effective date); see also Lindh v. Murphy, 521 U.S. 320, 322-23 , 117 S.Ct. 2059 , 138 L.Ed.2d 481 (1997).

Under the pre-AEDPA standards of review, we review de novo questions of law and mixed questions of law and fact. See Williams v. Taylor, 529 U.S. 362, 402 , 120 S.Ct. 1495 , 146 L.Ed.2d 389 (2000) (“Under the federal habeas statute as it stood in 1992, then, our precedents dictated that a federal court should grant a state prisoner’s petition for habeas relief if that court were to conclude in its independent judgment that the relevant state court had erred on a question of constitutional law or on a mixed constitutional question.”); Robinson v. Schriro, 595 F.3d 1086, 1099 (9th Cir.2010) (explaining that under pre-AEDPA law, federal courts owe no deference to a state court’s resolution of law or mixed questions of law and fact). However, “we presume that state court determinations of historical fact are correct.” Payton v. Woodford, 299 F.3d 815, 822 (9th Cir.2002) (en banc), vacated on other grounds by 538 U.S. 975 , 123 S.Ct. 1785 , 155 L.Ed.2d 662 (2003); see also 28 U.S.C. § 2254 (d) (1994); Woratzeck v. Stewart, 97 F.3d 329, 332 (9th Cir.1996); McKenna v. McDaniel, 65 F.3d 1483, 1490 (9th Cir.1995).

Here, the California Supreme Court’s ruling on whether or not the Green instruction applies is a question of law reviewed de novo.

Ill

Before addressing the merits of the habeas petition, we consider the State’s request that we exercise our discretion to invoke sua sponte the non-retroactivity bar of Teague v. Lane. Teague bars a federal court from retroactively applying “new constitutional rules of criminal procedure” on collateral review. 489 U.S. at 310 , 109 S.Ct. 1060 . If we were to invoke our discretion, we would need to determine whether Green’s “independent felonious purpose” element for a kidnap-murder special circumstance, see Williams v. Calderon, 52 F.3d 1465, 1476 (9th Cir.1995), would constitute a new constitutional rule of criminal procedure under Teague . Following oral argument, we requested supplemental briefing to address (1) what factors should inform our consideration whether to exercise our discretion to invoke Teague if we found waiver by the State; and (2) if we decided nonetheless to exercise our discretion, whether a Teague exception applied in light of Webster v. Woodford, 369 F.3d 1062 , 1067-69 & n. 2 (9th Cir.2004), Gilmore v. Taylor, 508 U.S. 333, 339-45 , 113 S.Ct. 2112 , 124 L.Ed.2d 306 (1993), Lambrix v. Singletary, 520 U.S. 518, 539-40 , 117 S.Ct. 1517 , 137 L.Ed.2d 771 (1997), and Clark v. Brown, 450 F.3d 898, 904-09 (9th Cir.2006).

“[C]ourts of appeals have [the] discretion, but are not required, to address a Teague defense raised for the first time on appeal (or, perhaps, even in a petition for rehearing).” Boardman v. Estelle, 957 F.2d 1523, 1536-37 (9th Cir.1992); see Collins v. Youngblood, 497 U.S. 37, 41 , 110 S.Ct. 2715 , 111 L.Ed.2d 30 (1990) (“Although the Teague rule is grounded in important considerations of federal-state relations, we think it is not ‘jurisdictional’ in the sense that this Court, despite a limited grant of certiorari, must raise and decide the issue sua sponte.”). Here, despite numerous opportunities to do so, the state repeatedly failed to raise the Teague defense as to the Green error. First, the state did not mention the defense as to Claim 24 in its answer to Pensinger’s first amended habeas petition before the district court, even though it argued Teague as to several other claims in its answer. See Schiro v. Farley, 510 U.S. 222, 228-29 , 114 S.Ct. 783 , 127 L.Ed.2d 47 (1994); Duckett v. Godinez, 67 F.3d 734 , 746 n. 6 (9th Cir.1995) (a state waives the Teague defense by not raising it in district court). Then, a full year prior to ruling on Pen-singer’s petition, the district court requested supplemental briefing “on the merits of Petitioner’s Claim 24 and on any procedural bar(s) to the claim.” (Emphasis added). The State’s supplemental briefing— again — failed to raise Teague as a procedural bar. Finally, following the district court’s grant of Pensinger’s petition on the basis of Claim 24, the State raised Teague in its motion to alter the judgment.

On this appeal, the State once again failed to properly allege its Teague defense. The State’s appellate brief raises Teague “only in passing” in a single paragraph towards the end of the brief without identifying “the new rule of constitutional law[,] ... why such a rule would not have been compelled by existing precedent ..., [and] why the rule contended for is not within one of Teague’s exceptions.” Arredondo v. Ortiz, 365 F.3d 778, 781-82 (9th Cir.2004) (“If a state seriously wishes to press Teague upon us, at a minimum Teague should be identified as an issue (indeed, the first issue) on appeal.”). In response to our request for supplemental briefing, the State admitted that it did not comply with the strictures of Arredondo in asserting the Teague defense on appeal.

In fairness, and despite Pensinger’s valid conviction for Michele’s murder and the kidnapping charges, on this record we cannot save the State from its repeated mistakes. Thrice the State “inadvertently” failed to properly assert Teague . The State offers no excuse for failing to raise Teague below. Nor does the State offer an excuse for failing to comply with Arredondo on appeal to us.

Its arguments to support our exercise . of discretion are likewise unavailing. The State argues that failure to consider Teague would be “pointless” because Pensinger would not be entitled to a Green instruction on retrial based on the California Supreme Court’s current interpretation of when the Eighth Amendment triggers the independent felonious intent requirement in the kidnap-murder special circumstance statute. While it is true that “the views of the federal courts of appeals do not bind the California Supreme Court when it decides a federal constitutional question,” Johnson v. Williams, — U.S. —, 133 S.Ct. 1088, 1098 , 185 L.Ed.2d 105 , reh’g denied, — U.S. —, 133 S.Ct. 1858 , 185 L.Ed.2d 858 (2013), “[t]he granting of a new trial places the parties in the same position as if no trial had been had,” Cal.Penal Code § 1180 (West 2015). In other words, Pensinger could present new evidence and arguments that would warrant a Green instruction under California’s interpretation of the Eighth Amendment. Furthermore, the State’s argument that a retrial of the special circumstance and penalty phase in a 33-year-old case would be costly is disingenuous — while we are sympathetic to the dilemma, the problem is one of its own making.

Given the extent of the State’s persistent waiver, its lack of adequate explanation, and unconvincing arguments in supplemental briefing, we decline to reach the Teague bar sua sponte. See Godinez v. Moran, 509 U.S. 389 , 397 n. 8, 113 S.Ct. 2680 , 125 L.Ed.2d 321 (1993) (declining to reach Teague defense “because petitioner [State warden] did not raise a Teague defense in the lower courts or in his petition for certiorari”); see also Schiro, 510 U.S. at 229 , 114 S.Ct. 783 (same); Arredondo, 365 F.3d at 781 (declining to address Teag-ue defense because it was “simply mentioned but not argued” (citation omitted)); Garceau v. Woodford, 281 F.3d 919, 920 (9th Cir.2002). As a result, our decision in Williams v. Calderon controls our review of Pensinger’s pre-AEDPA federal habeas petition. 52 F.3d 1465 .

IV

On the merits, the State challenges the district court’s holding that the trial court violated Pensinger’s constitutional rights by failing to instruct the jury sua sponte that — in order to find the kidnap-murder special circumstance true — there must be proof that the kidnapping was committed for an independent felonious purpose. Alternatively, even if a Green instruction was constitutionally required, the State contends the error was harmless. We agree with the district court that an instructional error occurred which was prejudicial, and affirm its grant of relief on the basis of Claim 24.

A

California’s death penalty statute requires the jury to find the existence of special circumstances to distinguish between defendants who are eligible for the death penalty and those who are not. See Cal.Penal Code § 190.2 (1978); Williams, 52 F.3d at. 1475-76; Green, 27 Cal.3d at 61 , 164 Cal.Rptr. 1 , 609 P.2d 468 . The felony-murder special circumstance applies to those murders “committed while the defendant was engaged in ... the commission of ... or the immediate flight after committing” one of certain enumerated felonies, including kidnapping. Cal.Penal Code § 190.2(a)(17)(B). At the time of Pensinger’s offense (1981) and trial (1982), the felony-murder special circumstance already required that the defendant have “an independent felonious purpose.” Green, 27 Cal.3d at 61 , 164 Cal.Rptr. 1 , 609 P.2d 468 ; see Clark, 450 F.3d at 915 (holding that Clark was constitutionally entitled to a Green instruction because Clark committed his crime in January 1982 and “the CALJIC instruction in place at the time of trial ... had specifically incorporated Green’s holding”).

The California Supreme Court developed this independent felonious purpose requirement to comply with the U.S. Supreme Court’s rulings in Furman v. Georgia, 408 U.S. 238 , 92 S.Ct. 2726 , 33 L.Ed.2d 346 (1972), and Gregg v. Georgia, 428 U.S. 153 , 96 S.Ct. 2909 , 49 L.Ed.2d 859 (1976). There, the Supreme Court found unconstitutional under the Eighth and Fourteenth Amendments death sentences imposed under statutes that left juries with untrammeled discretion to impose or withhold the death penalty. Furman, 408 U.S. at 313 , 92 S.Ct. 2726 (White, J., concurring); Gregg, 428 U.S. at 189, 199 , 96 S.Ct. 2909 . Furman and Gregg held that imposition of the death penalty should compel the jury to “focus on the particularized circumstances of the crime and the defendant” in order to reduce “the risk of wholly arbitrary and capricious” death sentences. Gregg, 428 U.S. at 189, 199 , 96 S.Ct. 2909 .

Guided by Furman and Gregg, Green explained that California’s felony-murder special circumstance statute “expressed a legislative belief that it was not unconstitutionally arbitrary to expose to the death penalty those defendants who killed in cold blood in order to advance an independent felonious purpose, e.g., who carried out an execution-style slaying of the victim of or witness to a holdup, a kidnap[p]ing, or a rape.” Green, 27 Cal.3d at 61 , 164 Cal.Rptr. 1 , 609 P.2d 468 . In other words, “Green held that a felony whose ‘sole object is to facilitate or conceal the primary crime’ of murder is ‘incidental,’ and therefore, does not qualify a defendant for the death penalty under the special circumstance statute.” Clark, 450 F.3d at 905-06 (emphasis added) (citing Green, 27 Cal.3d at 61 , 164 Cal.Rptr. 1 , 609 P.2d 468 ). Thus, “under Green , a felony qualified] under the special circumstance statute only if two requirements [a]re satisfied: (1) the felony, such as robbery or arson, must have been committed for a purpose ‘independent’ of the murder, and (2) the murder must have been committed in order to advance that ‘independent felonious purpose.’ ” Id. at 910, 164 Cal.Rptr. 1 , 609 P.2d 468 ; see also Phillips v. Ornoski, 673 F.3d 1168, 1193 (9th Cir.2012).

For instance, in Clark under the defendant’s theory of the case, “he set the fires [to the home] only for the purpose of driving David Gawronski out of the house so that he could shoot him.” Clark, 450 F.3d at 908 . Clark argued that he did not have an “an independent felonious purpose in committing arson.” Id. (internal quotation marks omitted). We held “Clark was entitled to an instruction that told the jury he was not guilty of the special circumstance if the arson was a felony whose ‘sole object [was] to facilitate ... the primary crime’ of murder.” Id. (citing Green, 27 Cal.3d at 61 , 164 Cal.Rptr. 1 , 609 P.2d 468 ).

Similarly, in Green , a husband killed his wife and subsequently took her clothes, rings and purse in order to conceal her identity. Green, 27 Cal.3d at 55 , 164 Cal.Rptr. 1 , 609 P.2d 468 . “The California Supreme Court held that this felonious robbery of the wife’s belongings was insufficient to support a felony-murder special circumstance conviction because Green did not commit the robbery for a reason independent of the murder, and then commit the murder to advance the purpose of committing the robbery.” Clark, 450 F.3d at 906 . “Rather, Green committed the robbery in order to facilitate or conceal the murder.” Id. “In other words, the robbery was ‘incidental’ to the murder.” Id.

However, since the Green decision, the California Supreme Court has narrowed the application of the Green instruction, while the Ninth Circuit has adopted Green’s broad holding. Compare People v. Kimble, 44 Cal.3d 480, 501 , 244 Cal.Rptr. 148 , 749 P.2d 803 (1988), with Williams, 52 F.3d at 1476 , and Clark, 450 F.3d at 910-11 (“[T]he California Supreme Court significantly changed the first requirement and entirely dispensed with the second ... that the murder have the purpose of advancing the ‘independent felonious purpose’ of the arson.”).

Under California’s current interpretation of Furman, Gregg, and the Eighth Amendment, a Green instruction is not always required. The California Supreme Court has held that the Green instruction “does not set out a separate element of the special circumstance” but rather acts to clarify that the murder must have taken place in furtherance of the accompanying special-circumstance felony. People v. Harris, 43 Cal.4th 1269, 1299 , 78 Cal.Rptr.3d 295 , 185 P.3d 727 (2008); see Kimble, 44 Cal.3d at 501 , 244 Cal.Rptr. 148 , 749 P.2d 803 (“[W]e reject the dissent’s novel suggestion that Green’s clarification of the scope of felony-murder special circumstances has somehow become an ‘element’ of such special circumstances, on which the jury must be instructed in all cases.... ”); People v. Monterroso, 34 Cal.4th 743, 767 , 22 Cal.Rptr.3d 1 , 101 P.3d 956 (2004). This is important because “[a] trial court has a sua sponte duty to instruct the jury on the essential elements of a special circumstance allegation.” People v. Mil, 53 Cal.4th 400, 409 , 135 Cal.Rptr.3d 339 , 266 P.3d 1030 (2012) (internal citations omitted).

The State heavily relies on California’s current interpretation to support the contention that no Eighth Amendment violation occurred in instructing the jury. Because the Green instruction (i.e., the second paragraph of CALJIC No. 8.81.17) does not constitute an element of the crime of special-circumstances murder, the State argues that the instruction is necessary only in limited circumstances. In support of its argument the State notes that the California Supreme Court has previously held that “a trial court has no duty to instruct on the second paragraph of CALJIC No. 8.81.17 unless the evidence supports an inference that the defendant might have intended to murder the victim without having had an independent intent to commit the specified félony.” People v. D’Arcy, 48 Cal.4th 257, 297 , 106 Cal.Rptr.3d 459 , 226 P.3d 949 (2010).

. However, the State fails to meaningfully distinguish the case we' must follow, Williams v. Calderon, 52 F.3d 1465 . In Williams, the petitioner challenged the kidnap-murder special circumstance, arguing that the trial court erred by failing to provide the jury a Green instruction and therefore “the jury’s finding this circumstance true was [] invalid.” Id. at 1475. We agreed that an “instructional error occurred” and interpreted the Green decision as requiring an instruction on the independent-felonious purpose. Id. at 1475-76. We further characterized the Green instruction as a “constitutional necessity, not mere state law nicety, for without this narrowing construction, the special circumstance would run afoul” of Furman and Gregg. Id. at 1476.

The State attempts to distinguish Williams by arguing that we did not reach the issue of whether or not a Green instruction was necessary in all special circumstance cases. A careful reading of the case, however, persuades us that Williams did indeed reach such a conclusion. Similar to the trial court in Pensinger, the trial court in Williams gave a jury instruction commensurate with the first paragraph of CALJIC No. 8.81.17, but omitted the second paragraph of that instruction. Williams v. Vasquez, 817 F.Supp. 1443, 1482 (E.D.Cal.1993). Considering our view of the Green instruction as a “constitutional necessity” in combination with the holding that an “instructional error occurred” when the trial court gave only the first half of CALJIC No. 8.81.17, Williams implicitly held that both paragraphs of CALJIC No. 8.81.17 were necessary to fulfill the strictures of Furman and Gregg . Therefore, because Pensinger’s kidnap-murder special circumstance jury instructions failed to comport with Fur-man, Gregg, Green, and Williams, the district court correctly concluded that an instructional error occurred.

“Where the error involves a failure to provide a narrowing instruction on a death special circumstance, we begin by asking whether it can be concluded, in light of the other instructions, that the jury necessarily found the omitted narrowing element.” Williams, 52 F.3d at 1476. Though not clear from its brief, the State seems to argue that because the jury was instructed on the elements of first-degree murder and kidnapping separately from the requirement for a special circumstance murder, the jury necessarily found the independent felonious intent. We found a similar argument insufficient in Williams and we are bound by that holding to reach the same conclusion here. See Williams, 52 F.3d at 1476.

Under Williams, where there is more than one plausible explanation for the defendant’s actions, we cannot conclude that the jury necessarily made the required independent felonious purpose finding. Id. at 1476-77. Here, the district court found that under the kidnapping jury instruction, the. jury could have convicted Pensinger of Michele’s kidnapping because it believed Pensinger kidnapped her “to inflict death” — under these facts, to murder Michele, Pensinger necessarily had to move her, making the kidnap “incidental” to the murder. The jury could also have convicted Pensinger of Michael, Jr.’s, kidnapping because it believed Pensinger kidnapped Michael, Jr., to “aid in the commission of [the] felony” of murdering Michele. In both circumstances, the jury would not have found a purpose for kidnapping independent of Michele’s murder. On the other hand, the jury could have concluded that Pensinger kidnapped Michele with the independent purpose of molesting her, and that he formed the intent to murder her after the kidnapping. Because evidence of Pensinger’s intent is subject to more than one interpretation, we cannot conclude the jury necessarily found the omitted narrowing element. Id. The district court properly found the remaining jury instructions did not cure the error.

Next, we consider whether the California Supreme Court cured the invalid instruction, and, if not, whether that omission was harmless under Brecht v. Abrahamson, 507 U.S. 619, 637 , 113 S.Ct. 1710 , 123 L.Ed.2d 353 (1993).

B

The California Supreme Court can cure an invalid instruction in two ways. Morales v. Woodford, 388 F.3d 1159, 1171 (9th Cir.2004). First, it can affirm the trial court if it finds beyond a reasonable doubt that the same result would have been obtained “without relying on the unconstitutional aggravating circumstance”— that is to say, the error was harmless. Id. (citing to Valerio v. Crawford, 306 F.3d 742, 756-57 (9th Cir.2002) (en banc)). Second, the California Supreme Court can invoke the method described in Clemons v. Mississippi, 494 U.S. 738, 748 , 110 S.Ct. 1441 , 108 L.Ed.2d 725 (1990), by re-weighing the aggravating and mitigating circumstances to test whether the verdict could stand without the improperly introduced factor. Id.

Here, because the California Supreme Court did not find error in the kidnap-murder special circumstance finding, it did not attempt to cure the invalid jury instruction. Pensinger, 52 Cal.3d at 1255-56 , 278 Cal.Rptr. 640 , 805 P.2d 899 . Instead, it held that there was “no substantial evidence that defendant’s sole purpose at the inception of the kidnapping was to murder [the baby].” Id. at 1255 , 278 Cal.Rptr. 640 , 805 P.2d 899 .

“In the absence of the requisite ‘close appellate scrutiny’ by the state courts” a federal appellate court must conduct its own harmless error analysis. Morales, 388 F.3d at 1171 .

C

An error in the instruction of a death penalty special circumstance is subject to Brecht’s harmless error review. Williams, 52 F.3d at 1476 ; see also Morales, 388 F.3d at 1171-72. Under Brecht , an error is harmless unless it can be found that it “had substantial and injurious effect or influence in determining the jury’s verdict.” Brecht, 507 U.S. at 637 , 113 S.Ct. 1710 (quoting Kotteakos v. United States, 328 U.S. 750, 776 , 66 S.Ct. 1239 , 90 L.Ed. 1557 (1946)) (internal quotations marks omitted). A habeas petitioner must establish that the error resulted in “actual prejudice.” Id. (internal quotation marks omitted). However, where a judge in a habeas proceeding is in “ ‘grave doubt as to the harmlessness of the error,’ the habeas ‘petitioner must win.’ ” California v. Roy, 519 U.S. 2, 5-6 , 117 S.Ct. 337 , 136 L.Ed.2d 266 (1996) (citing O’Neal v. McAnnich, 513 U.S. 432, 437 , 115 S.Ct. 992 , 130 L.Ed.2d 947 (1995)). We have previously noted that an error is “not harmless as a matter of law” when “our invalidation of the special circumstance eliminated the only remaining special circumstance.” Morales, 388 F.3d at 1172 (citing to Wade v. Calderon, 29 F.3d 1312, 1322-23 (9th Cir.1994), overruled on other grounds by Rohan ex rel. Gates v. Woodford, 334 F.3d 803, 815 (9th Cir.2003)).

Here, the jury found Pensinger eligible for the death penalty without having to make any determination whether there was an “independent felonious purpose” to the kidnapping of Michele Melan-der. Although the prosecutor presented evidence of at least two different independent purposes for Michele Melander’s kidnapping, the instruction given to the jury required the jury to find only that the murder occurred while Pensinger was “engaged in kidnapping in violation of California Penal Code Section 207.” Thus, it was possible for the jury merely to find that the kidnapping was incidental to the murder' — that is, during the course of committing murder, Pensinger “happened] to engage in ancillary conduct that technically constitutes [a kidnapping] or one of the other listed felonies.” See Green, 27 Cal.3d at 62 , 164 Cal.Rptr. 1 , 609 P.2d 468 . Finally, the only special circumstance which remains upholding Pensinger’s death sentence is the deficient kidnap-murder special circumstance. Cf. Williams, 52 F.3d at 1479-80 (finding no prejudice on Green instructional error because the jury found several other valid special circumstances). “When a jury is the final sentencer, it is essential that the jurors be properly instructed regarding all facets of the sentencing process. It is not enough to instruct the jury in the bare terms of an aggravating circumstance that is unconstitutionally vague on its face.” Walton v. Arizona, 497 U.S. 639, 653 , 110 S.Ct. 3047 , 111 L.Ed.2d 511 (1990), overruled on other grounds by Ring v. Arizona, 536 U.S. 584 , 122 S.Ct. 2428 , 153 L.Ed.2d 556 (2002) (citing Maynard v. Cartwright, 486 U.S. 356 , 108 S.Ct. 1853 , 100 L.Ed.2d 372 (1988), and Godfrey v. Georgia, 446 U.S. 420 , 100 S.Ct. 1759 , 64 L.Ed.2d 398 (1980)). Therefore, we cannot here uphold the kidnap-murder special circumstance on a harmless error theory. The district court properly granted Pen-singer’s petition on the basis of Claim 24.

y

Finally, we consider Pensinger’s contention that his trial counsel was ineffective in failing to request a jury instruction in accordance with People v. Green, during the guilt phase.

A meritorious ineffective assistance of counsel claim must demonstrate: (1) “that counsel’s representation fell below an objective standard of reasonableness”; and (2) that the deficient performance prejudiced the defense, which requires a showing that “there is a reasonable probability that, but for counsel’s unprofessional errors, the result of the proceeding would have been different.” Strickland v. Washington, 466 U.S. 668, 688, 694 , 104 S.Ct. 2052 , 80 L.Ed.2d 674 (1984).

Under the pre-AEDPA standard of review, a state court’s conclusion as to whether counsel rendered ineffective assistance is a mixed question of law and fact, id. at 698 , 104 S.Ct. 2052 , subject to de novo review, Williams, 529 U.S. at 400 , 120 S.Ct. 1495 . However, the state court findings of fact made in the course of deciding an ineffectiveness claim are questions of fact, subject to “a presumption of correctness.” Thompson v. Keohane, 516 U.S. 99, 111 , 116 S.Ct. 457 , 133 L.Ed.2d 383 (1995); Lambert v. Blodgett, 393 F.3d 943, 976 (9th Cir.2004). “Consequently, a federal court reviewing a state court conclusion on a mixed issue involving questions both of fact and law must first separate the legal conclusions from the factual determinations that underlie it.” Lambert, 393 F.3d at 977-78.

A

A counsel’s performance is deficient if his or her representation was unreasonable “under prevailing professional norms.” Strickland, 466 U.S. at 688 , 104 S.Ct. 2052 . “Judicial scrutiny of counsel’s performance must be highly deferential ...'. A fair assessment of attorney performance requires that every effort be made to eliminate the distorting effects of hindsight.” Id. at 689 , 104 S.Ct. 2052 . The court “must indulge a strong presumption that counsel’s conduct falls within the wide range of professional assistance; that is, the defendant must overcome the presumption that, under the circumstances, the challenged action might be considered sound trial strategy.” Id. (internal quotation marks omitted).

Where counsel pursues one theory of the defense over another, counsel’s lack of request for a jury instruction on the alternate theory does not constitute deficient performance. See Clabourne v. Lewis, 64 F.3d 1373, 1382-83 (9th Cir.1995) (“Clabourne was pursuing an insanity defense, and that defense might have been less credible if Clabourne had disavowed his confession.... [Thus,] the failure to request a voluntariness instruction [regarding his confession] ... did not amount to ineffective assistance.”); United States v. Chambers, 918 F.2d 1455, 1461-62 (9th Cir.1990) (“Chambers’ trial counsel chose to pursue an identity defense rather than challenge Chambers’ possession of the' cocaine .... [T]rial counsel did not render deficient performance by failing to request a [possession] instruction.”).

Here, the district court relied on Claboume and Chambers , holding that failure to request a Green instruction would meet the prejudicial prong of the Strickland standard, but not the deficient performance prong. We agree. Defense counsel’s theory was that Pensinger did not kidnap or murder Michele. Instead, he argued that Vickie, Michele’s mother, had both the motive and opportunity to have Michele killed. Thus, requesting a jury instruction requiring Pensinger to have an independent felonious purpose in kidnapping Michele did not comport with defense counsel’s theory of the case that Pensinger did not murder Michele.

Pensinger contends that the facts in Clabourne and Chambers are distinguishable because Pensinger’s Green instruction was not an instruction that the defense had to request. Rather, that since the trial court had a duty to instruct the jury, by extension, trial counsel was ineffective in not asking for the instructions on all basic elements of the kidnapping special circumstance, including the Green instruction. Pensinger inappropriately conflates the trial court’s duty with counsel’s. Because Pensinger’s defense theory was that he did not kidnap the children or murder Michele, defense counsel did not have a duty to request a Green instruction and, consequently, his failure to request one did not render his performance deficient. Chambers, 918 F.2d at 1461-62 ; Clabo urne, 64 F.3d at 1382-83 . Therefore, the district court properly denied Pensinger’s petition for relief on the basis of Claim 12(BB).

VI

The facts of five-month-old Michele’s murder are horrific. While Pensinger’s convictions for the first-degree murder of Michele Melander and the kidnapping of Michael, Jr., and Michele are unaffected by our decision — under our pre-AEDPA case law — the district court properly vacated the kidnap-murder special circumstance finding, which alone supported Pen-singer’s death sentence. Under Williams v. Calderon, an instructional error occurred when the trial court omitted the Green instruction requiring the jury to find an independent felonious purpose to kidnap Michele. Williams, 52 F.3d at 1476 . Even in light of other instructions, the jury did not necessarily find the independent felonious purpose. And, under Brecht , the omission of the Green instruction in the kidnap-murder special circumstance was not harmless as a matter of law because our invalidation would eliminate the only remaining special circumstance supporting the capital sentence imposed.

The district court properly denied Pen-singer’s ineffective assistance of counsel claim because trial counsel’s failure to request a Green instruction comported with the theory of his defense.

AFFIRMED.

. At the time of Pensinger’s trial in 1982, the trial court used CALJIC No. 8.81.17, Fourth Edition 1980 Rev. . 27 Cal.3d 1 , 164 Cal.Rptr. 1 , 609 P.2d 468 (1980), . We decline to expand the certificate of appealability to include Pensinger’s uncertified claims because Petitioner has not made "a substantial showing of the denial of a consti-national right.” 28 U.S.C. § 2253 (c)(2) (2012); see Slack v. McDaniel, 529 U.S. 473, 483 , 120 S.Ct. 1595 , 146 L.Ed.2d 542 (2000). . The instruction given in Williams was: [i]t is further charged that [defendant] was personally present and physically aided or committed the acts causing the death of Lourdes Meza and that the murder of Lourdes Meza was willful, deliberate and premeditated and was committed during the commission or attempted commission of kidnapping in violation of Section 207 of the California Penal Code. Williams v. Vasquez, 817 F.Supp. at 1482 . The instruction in Pensinger was: If you find the defendant in this case guilty of murder of the first degree, you must then determine if the murder was committed under one or more of the following special circumstances: One, while said defendant, Brett Patrick Pensinger, also known as Panama Red, was engaged in kidnap [p]ing in violation of California Penal Code Section 207. . We are not alone in interpreting Green as requiring an independent felonious purpose instruction in all felony-murder cases to comply with the Constitution. See Kimble, 44 Cal.3d at 517, 244 Cal.Rptr. 148 , 749 P.2d 803 (Mosk, J., dissenting) ("In Green , the court squarely held that the felony-murder special circumstance must be construed to require a finding of independent felonious purpose. ... [T]he majority’s attempt to present advancement of an independent felonious purpose as merely a kind of nonessential clarifying’ or 'amplifying' gloss is unsuccessful.”). . The superior court provided the following kidnapping juiy instruction: If a person moved away is incapable of consenting thereto by reason of immaturity or mental condition, then the person moving him away is guilty of kidnapping only if you are convinced beyond a reasonable doubt that before the movement the person formed a specific intent to do the moving for an illegal purpose or with an illegal intent and only if you are convinced beyond a reasonable doubt that he knowingly or having reason to know that he had no legal right to do so took, enticed, or kept from the legal custodian a child less than eighteen years of age without the custodian’s consent and only if you're convinced beyond a reasonable doubt that he knowingly restrained another person with the intent to, [1] hold the victim for ransom, as a shield or hostage; or [2] for involuntaiy servitude; or [3] to inflict death, physical injury, child endangering or sexual offenses on the victim, to detain or conceal such child from a parent, of to otherwise aid in the commission of a felony; or [4] place the victim or a third person in the reasonable apprehension of imminent physical injury to the victim or such third person. (Emphasis added). . The State's two different theories were: (1) Pensinger wanted to and did sexually molest Michele; and (2) Pensinger wanted to "strike back” at Vickie Melander and her husband for the theft of his rifle.- . At closing, defense counsel argued that at the time of the murder Vickie felt desperate, had two children, was pregnant with a third, had no place to stay, and was married to a man who would not work. Defense counsel argued that Vickie's children interfered with the way she wanted to live, and that Vickie did not have the money for the special formula that Michele’s medical condition required.