Opinion by Judge WALLACE; Concurrence by Judge FERNANDEZ; Concurrence by Judge RYMER; Concurrence by Judge KOZINSKI; Dissent by Judge PREGERSON.
WALLACE, Circuit Judge:Sheriff Don Horsley of San Mateo County, California, (State) appeals from the district court’s issuance of a writ of habeas corpus in favor of Jose Napolean Santamaría. The district court had jurisdiction under 28 U.S.C. § 2254. We have jurisdiction over this timely appeal pursuant to 28 U.S.C. §§ 1291 and 2253. Because Santamaría argues that retrial will violate his constitutional rights, we may review his petition even though it is pretrial. See 28 U.S.C. § 2241(c)(3); Braden v. Judicial Circuit Court of Ky., 410 U.S. 484, 488-90 (majority) and 503 (Rehnquist, J., dissenting), 93 S.Ct. 1123, 1126-27, 1133-34, 35 L.Ed.2d 443 (1973). Beyond that, the State has not asked us to abstain or demand further exhaustion on Santamaria’s part, nor do we see any *1244other basis for deferring a decision. Therefore, we address the merits of Santamaria’s petition. We granted rehearing en banc to determine whether to overrule Pettaway v. Plummer, 943 F.2d 1041 (9th Cir.1991) (Pettaway). We reverse.
I
In February 1989, a California jury found Santamaría guilty of murder and robbery, but found “not true” a sentence enhancement charge, under California Penal Code § 12022(b), that he personally used a deadly weapon (a knife) in the commission of a felony. See People v. Santamaria, 8 Cal.4th 903, 909, 35 Cal.Rptr.2d 624, 884 P.2d 81 (1994) (Santamaria). A state appellate court reversed the murder conviction, holding that an 11-day continuance during jury deliberations was prejudicial error. Id. at 909, 35 Cal.Rptr.2d 624, 884 P.2d 81, citing People v. Santamaria, 229 Cal.App.3d 269, 280 Cal.Rptr. 43 (1991).
On remand, Santamaría filed a motion to, among other things, “preclude prosecution’s reliance on theory adjudicated in defendant’s favor at first trial.” Id. The trial court granted the motion, ruling that the collateral estoppel component of the Double Jeopardy Clause barred the prosecution “from retrying the defendant on the theory that he personally used the knife during the killing.” Id. The State subsequently stated that it was unable to proceed in light of the court’s ruling, and the case was dismissed. The California Court of Appeal affirmed the trial court’s dismissal of the case, but the California Supreme Court reversed. That court held “that collateral estoppel does not apply,” id. at 922, 35 Cal.Rptr.2d 624, 884 P.2d 81, and remanded the case to the trial court with instructions to reinstate the charges.
Santamaría then filed a petition for a writ of habeas corpus in the United States District Court for the Northern District of California. The district court held that our decision in Pettaway compelled the conclusion that the Double Jeopardy Clause bars the State from arguing at retrial that Santamaría used a knife to commit murder. Therefore, the district court issued the writ. A panel of this court affirmed the district court, holding that Pettaway controlled the outcome of this case. Santamaria v. Horsley, 110 F.3d 1352, 1357 (9th Cir.1997).
The State, Santamaría, and the California Supreme Court agree that this case is factually indistinguishable from Pettaway, and that the only substantial legal issue before us is the continuing vitality of that decision. See Santamaria, 8 Cal.4th at 923, 35 Cal.Rptr.2d 624, 884 P.2d 81 (“People v. Pettaway ... involved virtually the same issue and procedural posture as this case, except that there the weapon enhancement that the jury found not true was for use of a firearm, not a knife.”).
We review de novo a district court’s decision to issue a writ of habeas corpus. Martinez-Villareal v. Lewis, 80 F.3d 1301, 1305 (9th Cir.), cert. denied, — U.S. -, 117 S.Ct. 588, 136 L.Ed.2d 517 (1996). The habeas corpus provisions of the Antiterrorism and Effective Death Penalty Act of 1996 (amendments to 28 U.S.C. §§ 2241-2255) do not apply retroactively to this appeal. Lindh v. Murphy, — U.S. -, -, 117 S.Ct. 2059, 2063, 138 L.Ed.2d 481 (1997).
II
At the outset, we identify what this case is not about. Santamaría does not argue that his retrial for murder is barred by the Double Jeopardy Clause of the Fifth Amendment made applicable to the States through the Fourteenth Amendment. Nor does the State argue that it should be permitted to seek the weapon enhancement on retrial. Nor are we concerned with whether collateral estoppel should be limited to subsequent trials, as opposed to retrials; we assume without deciding that the doctrine does apply to retrials. The sole issue we address is whether the jury’s verdict of “not true” on the use of a knife on a weapon enhancement charge precludes the State from presenting evidence and arguing in a retrial that Santamaría used the knife to commit murder.
A.
Collateral estoppel, or issue preclusion, “means simply that when an issue of ultimate fact has once been determined by a valid and final judgment, that issue cannot *1245again be litigated between the same parties in any future lawsuit.” Ashe v. Swenson, 397 U.S. 436, 443, 90 S.Ct. 1189, 1194, 25 L.Ed.2d 469 (1970) (Ashe). As the Court has instructed:
[T]he rule of collateral estoppel in criminal cases is not to be applied with the hyper-technical and archaic approach of a 19th century pleading book, but with realism and rationality. Where a previous judgment of acquittal was based upon a general verdict, as is usually the case, this approach requires a court to “examine the record of a prior proceeding, taking into account the pleadings, evidence, charge, and other relevant matter, and conclude whether a rational jury could have grounded its verdict upon an issue other than that which the defendant seeks to foreclose from consideration.”
Id. at 444, 90 S.Ct. at 1194.
In Ashe, several bandits robbed six men playing poker. Ashe was tried and acquitted for robbing one of the six men. The State then successfully tried him for robbing another victim. Because the robbery of the second poker player was a separate crime, the Double Jeopardy Clause did not bar the second trial. 397 U.S. at 437-40, 446, 90 S.Ct. at 1190-92, 1195. However, the Court reversed, holding that the Double Jeopardy Clause contained a collateral estoppel element that barred relitigation of any ultimate fact necessarily decided in an earlier trial. Id. at 442-43, 445, 90 S.Ct. at 1193-94, 1195. Based on an evaluation of the record, the Court held that the only contested issue was identity, and therefore .the acquittal in the first trial indicated that the State had failed to prove beyond a reasonable doubt that Ashe was one of the bandits. Id. at 445, 90 S.Ct. at 1195. The State was therefore barred by the doctrine of collateral estoppel from trying Ashe for the robbery of any of the other poker players, since identity would be an ultimate issue in each such trial.
In Pettaway, following Ashe, we held that a jury finding of “not true” on a California sentence-enhancement charge implicates the collateral estoppel component of the Double Jeopardy Clause. 943 F.2d at 1047-48. We reasoned that if a defendant’s conviction is subsequently reversed on appeal, a “not true” determination bars the prosecution from relying at retrial on any theory of the offense factually inconsistent with it. In Pettaway, the jury found the defendant guilty of murder, but found “not true” two sentence enhancement charges that he personally used a firearm and personally inflicted great bodily injury. The murder conviction was reversed on appeal, and at retrial the State proposed to introduce evidence tending to show that Pettaway personally shot the victim. We held that a retrial on that theory would be inconsistent with the first jury’s “not true” determinations and would therefore violate the Double Jeopardy Clause.
B.
The California Supreme Court’s subsequent clarification of state law in San-tamaría has shown that Pettaway ascribed too much significance to the jury’s “not true” response on the weapon enhancement determination. We recognize that “[t]he preclu-sive effect of the jury’s verdict ... is a question of federal law which we must review de novo.” Schiro v. Farley, 510 U.S. 222, 232, 114 S.Ct. 783, 790, 127 L.Ed.2d 47 (1994). However, Santamaria is particularly relevant because it sets forth the state law requirements for proving murder. See, e.g., Wainwright v. Goode, 464 U.S. 78, 84, 104 S.Ct. 378, 382, 78 L.Ed.2d 187 (1983) (per curiam) (“[T]he views of the state’s highest corut with respect to state law are binding on the federal courts.”).
Pettaway held that since the jury convicted Pettaway of murder but rejected the weapons enhancement charge, “[t]he jury necessarily decided that Pettaway did not fire the fatal shots.” 943 F.2d at 1046. Thus, Pettaway restricted the State to an aiding and abetting theory. This conclusion is incorrect.
There is no dispute that the jury determination on the weapons enhancement issue properly barred the State from seeking the enhancement on retrial, because the ultimate fact of whether the State had proven the weapon use beyond a reasonable doubt for the enhancement had been determined already. But this determination did not necessarily mean that the jury had therefore *1246found Pettaway guilty of murder only as an aider and abettor. First, we must bear in mind that “an acquittal is not a finding of any fact. An acquittal can only be an acknowledgment that the government failed to prove an essential element of the offense beyond a reasonable doubt.” United States v. Watts, — U.S. -, -, 117 S.Ct. 633, 637, 136 L.Ed.2d 554 (1997) (per curiam) (Watts), quoting United States v. Putra, 78 F.3d 1386, 1394 (9th Cir.1996) (Wallace, J., dissenting). Second, California allows a jury to convict a defendant for murder without unanimous agreement as to whether he was guilty as an aider and abettor or as a direct perpetrator. Santamaria, 8 Cal.4th at 918, 35 Cal.Rptr.2d 624, 884 P.2d 81; see generally Schad v. Arizona, 501 U.S. 624, 630-31, 111 S.Ct. 2491, 2496-97, 115 L.Ed.2d 555 (1991) (opinion of Justice Souter, joined by Chief Justice Rehnquist and Justices Kennedy and O’Con-nor) (upholding Arizona’s procedure of allowing a jury to convict a defendant of first-degree murder without agreement as to a particular theory). Thus, California does not require the individual jurors to choose a particular theory of murder beyond a reasonable doubt, “so long as each is convinced of guilt.” Santamaria, 8 Cal.4th at 919, 35 Cal.Rptr.2d 624, 884 P.2d 81.
Pettaway’s two verdicts may be harmonized by concluding that the jury found that Pettaway was guilty as an aider and abettor. However, it is also conceivable that all twelve jurors were convinced beyond a reasonable doubt that Pettaway played some role, either as the shooter or as an aider and abettor, without ascertaining exactly which role. We have no way of knowing, because these alternatives (and perhaps others) are rationally consistent with the jury’s verdict in that case.
Santamaría points out that the jury was never instructed that it did not need to reach agreement as to his particular role in the murder, and hence, could not have relied upon this “either/or” theory. However, he bears the burden of showing “that the issue whose relitigation he seeks to foreclose was actually decided in the first proceeding.” Dowling v. United States, 493 U.S. 342, 350, 110 S.Ct. 668, 673, 107 L.Ed.2d 708 (1990) (Dowling). Furthermore, he must convince us that no “rational jury could have grounded its verdict upon an issue other than that which the defendant seeks to foreclose from consideration.” Ashe, 397 U.S. at 444, 90 S.Ct. at 1194, quoting Mayers & Yarbrough, Bis Vexari: New Trials and Successive Prosecutions, 74 Harv. L.Rev. 1, 38-39.
This he did not and cannot do. The State’s evidence in this case came largely by way of accomplice Anthony Nubia, who testified that he saw Santamaría hugging the victim’s neck and stabbing him. Santamaria, 8 Cal.4th at 909, 35 Cal.Rptr.2d 624, 884 P.2d 81. Santamaria, on the other hand, testified that on the day of the murder, he had driven a friend to pick up a paycheck; he denied any involvement in the crime. People v. Santamaria, 229 Cal.App.3d at 274, 280 Cal.Rptr. 43. By convicting him of murder, the jury obviously rejected Santamaria’s alibi. The jury could have had doubts about the complete veracity of Nubia’s testimony, but the thrust of the evidence was that Santamaria was the active murderer, and there was little, if any, evidence that Santamaria aided and abetted Nubia in the killing. We cannot say that the split verdict, even in the absence of a specific “either/or” instruction, indicates that a rational jury could only conclude that Nubia had not only perjured himself but also was the sole active participant in the murder.
Pettaway also held that the possibility that the second jury could conclude that Pettaway shot the victim himself, thereby reaching a conclusion “directly contrary” to that of the first jury, would be “abhorrent to the principles underlying the Double Jeopardy Clause.” 943 F.2d at 1047. This conclusion is erroneous as well. The second jury, if it convicted Pettaway on retrial based partially (or even solely) on evidence that he shot the victim, would be concluding only that Petta-way committed murder. See Santamaria, 8 Cal.4th at 923 n. 10, 35 Cal.Rptr.2d 624, 884 P.2d 81 (“The jury returns a verdict of guilt or innocence of the charge, not a verdict on any particular theory.”).
Because there is more than one rational conclusion that can be drawn from the first jury’s verdict, Pettaway erred in restricting the State on retrial solely to the aiding and abetting theory. See, e.g., Ashe, 397 U.S. at 444 & n. 9, 90 S.Ct. at 1194 & n. 9 (holding *1247that the question is whether a rational jury could have based its decision on any other conclusion). We therefore hold that the jury’s determination on the weapon enhancement issue cannot restrict the State to retrying Santamaría solely on an aiding and abetting theory of murder.
C.
We next address whether the State should be precluded from retrying Santamaria on the theory that he personally used the knife to kill the victim, while allowing retrial on the theories that he aided and abetted the murder, or that he was a direct participant other than using the knife in the murder. See, e.g., Santamaria, 8 Cal.4th at 932-33, 35 Cal.Rptr.2d 624, 884 P.2d 81 (Mosk, J., concurring and dissenting).
To resolve this complex issue, we consider whether the use of a knife is an ultimate fact for the purposes of a murder conviction under California law. If it is not, then collateral estoppel will not preclude the government from introducing evidence that Santamaría stabbed the victim, because collateral estop-pel does not “exclude in all circumstances ... relevant and probative evidence that is otherwise admissible under the Rules of Evidence simply because it relates to alleged criminal conduct for which a defendant has been acquitted.” Dowling, 493 U.S. at 348, 110 S.Ct. at 672; see also United States v. Seley, 957 F.2d 717, 723 (9th Cir.1992) (“If an act that could have been proved to a lesser degree than that required for conviction is for some reason probative in a subsequent trial, it need not be excluded because of the prior acquittal.”); cf. Watts, — U.S. at -, 117 S.Ct. at 637 (allowing the consideration at sentencing of conduct for which a defendant has been acquitted because of the lower burden of proof at sentencing).
In Dowling, the defendant was tried for the robbery of a bank where the robber had worn a ski mask and carried a small handgun. The government sought to introduce evidence that, two weeks after the bank robbery, Dowling attempted to rob a woman, while wearing a ski mask and carrying a small handgun. Dowling, 493 U.S. at 344, 110 S.Ct. at 670. Dowling, however, had been acquitted of this robbery, and he argued that the government should be collaterally estopped from introducing the evidence.
The Court held that “unlike the situation in Ashe v. Swenson, the prior acquittal did not determine an ultimate issue in the present case.” 493 U.S. at 348, 110 S.Ct. at 672. The difference was that in Ashe, the first jury’s acquittal “could only have meant that the jury was unable to conclude beyond a reasonable doubt that the defendant was one of the bandits.” Id. in the second trial, the government would still have to prove beyond a reasonable doubt that Ashe was one of the robbers, a determination that would be directly contrary to the verdict in the first trial. Id. On the other hand, in Dowling, the government did not have to establish beyond a reasonable doubt that Dowling was the person who entered the second victim’s home. Thus, collateral estoppel was not applicable “[b]ecause a jury might reasonably conclude that Dowling was the masked man who entered [the second victim’s] home, even if it did not believe beyond a reasonable doubt that Dowling committed the crimes charged at the first trial.” Id. at 348-49, 110 S.Ct. at 672-73.
In this case, the State failed to prove beyond a reasonable doubt the ultimate fact that Santamaría used a knife for the weapon enhancement in the first trial. However, to convict him of murder under California law, the State is not required to prove beyond a reasonable doubt that Santamaria used a knife. Santamaria, 8 Cal.4th at 918-19, 35 Cal.Rptr.2d 624, 884 P.2d 81. Therefore, the use of a knife is not an ultimate fact for the retrial, and the State cannot be precluded from presenting evidence that Santamaria stabbed the victim.
There is at least a theoretical possibility that in the second trial all twelve jurors could convict Santamaría based on individual determinations that the State proved beyond a reasonable doubt that he used the knife, resulting iii a verdict contrary to that rendered by the first jury. See Santamaria, 8 Cal.4th at 934, 35 Cal.Rptr.2d 624, 884 P.2d 81 (Mosk, J., concurring and dissenting) (arguing that the jury should be instructed “only that it could riot find that defendant was guilty as a principal as a direct and *1248active perpetrator solely through his personal use of a knife ”). But even if we should rest our decision upon such a theoretical possibility, such a verdict would be directly contrary to that of the first jury only if no juror would also find Santamaría guilty under either of the other two theories of murder. Because California has chosen to allow murder -to be proven without unanimous agreement as to the particular theory, any juror who thought that the State had proven beyond a reasonable doubt that Santamaría used a knife to kill the victim would necessarily also conclude that the State had proven beyond a reasonable doubt that Santamaría had played a culpable role in killing the victim.
D.
Santamaría argues that the “either/or” theory violates the Sixth Amendment and is logically incoherent. Santamaria’s Sixth Amendment argument relies on Mitchell v. Prunty, 107 F.3d 1337, 1339 n. 2 (9th Cir.) (“Special findings, by contrast, are dispositive of the questions put to the jury. Having agreed to the questions, the government cannot now ask us to ignore the answers; to do so would be a clear violation of petitioner’s Sixth Amendment rights.”), cert. denied, — U.S. -, 118 S.Ct. 295, 139 L.Ed.2d 227 (1997). In Mitchell, a California state jury convicted Mitchell of second-degree murder, but found a weapon enhancement to be not true and rendered a special verdict that he did not drive the car that ran over the victim. Id. We reviewed the sufficiency of the evidence to support Mitchell’s conviction only under an aiding and abetting theory. Id. at 1340.
Mitchell concerned sufficiency of the evidence, not collateral estoppel. It, however, shared Pettaway’s flawed premise that if the jury returned a not true verdict on a weapon enhancement question but also returned a murder conviction, it must have concluded that the defendant, aided and abetted. For the reasons we have discussed earlier, that premise is inconsistent with the substantive California state law. To the extent Mitchell is inconsistent with this opinion, we overrule it.
Finally, Santamaría has not convinced us that the “either/or” theory is logically incoherent. To begin with, the requirements for proving murder are entirely a matter of state law so long as they are not constitutionally infirm, an issue that has been essentially resolved here by Schad.
In any event, the fact that the State failed to prove beyond a reasonable doubt in the first trial that Santamaría used a knife does not therefore mean that the State logically can prove murder only by showing that he aided and abetted. The State’s burden under the “either/or” theory is to prove beyond a reasonable doubt that Santamaría used the knife or aided and abetted, but it can meet this burden even if it fails to prove beyond a reasonable doubt that he used the knife and it fails to prove beyond a reasonable doubt that he aided and abetted, so long as the jury is convinced beyond a reasonable doubt that he was culpably involved in the killing.
Indeed, the California Supreme Court persuasively points out that the true logical incoherence lies in Santamaria’s position. Requiring the State to prove either direct perpetration or aiding and abetting beyond a reasonable doubt could result in acquittal in a situation where the jury is convinced beyond a reasonable doubt that two co-defendants committed a crime, but is not sure beyond a reasonable doubt as to which defendant was the direct perpetrator and which was the aider and abettor. Santamaria, 8 Cal.4th at 920 n. 8, 35 Cal.Rptr.2d 624, 884 P.2d 81, quoting People v. Perez, 21 Cal.App.4th 214, 222, 26 Cal.Rptr.2d 691 (1993).
Moreover, contrary to Santamaria’s assertion, the “either/or” theory does not “spell the end for the doctrine of collateral estoppel after a special verdict adverse to the state.” As pointed out in Dowling and Seley, preclu-sive effect can be given to special verdicts on ultimate facts in subsequent relitigation where the burden of proof remains the same. Thus, had identity been at issue, and had there been a special verdict returned with respect to identity, collateral estoppel might well bar retrial.
In conclusion, we overrule Pettaway. We reverse the district court’s issuance of the writ of habeas corpus.
REVERSED.