The trial court’s refusal to instruct on misdemeanor distribution of an imitation controlled substance (Health & Saf. Code, § 11680)1 is, in my view, reversible error.
I.
The majority concludes that instructions on misdemeanor distribution of an imitation controlled substance (§ 11680) were not required even though this lesser related offense is “closely related” to the charged offense (§ 11355) within the meaning of People v. Geiger (1984) 35 Cal.3d 510, 531 [199 Cal.Rptr. 45, 674 P.2d 1303, 50 A.L.R.4th 1055]. This is so, the majority reasons, because “the misdemeanor distribution offense for which Hill sought instruction was ‘lesser’ only in terms of penalty. Its elements so closely resembled those of the charged in-lieu sale that trial counsel would have had to urge jurors to accept, not reject, evidence of the greater offense but return a verdict only on the lesser.” (Maj. opn., ante, p. 44, italics in original.) In other words, denying the lesser related offense instruction does *49not offend Geiger because “If Hill was guilty of the lesser, on these facts, he was also guilty of the greater.” (Id., at p. 45.)
The theory that Geiger does not apply to offenses so similar to the charged offense that the only difference is the penalty—a theory never advanced by the People—turns Geiger on its head. To say that Geiger does not apply to an admittedly related offense shown by the evidence because it is lesser than the charged offense “only in terms of penalty” renders the reason the defendant wishes to invoke it the basis for excluding it. If a related offense is not within Geiger “merely” because it prescribes a lesser penalty, what then is necessary to bring such an offense within the rule? The requirement, my colleagues apparently believe, is that it not be too closely related to the offense charged by the district attorney. This is an unreasonable corruption of Geiger. The assignment by the Legislature of different penalties for what appears to be the same conduct justifies greater, not lesser, protection of the sort Geiger provides.
The majority’s analysis is not only unreasonable, but has the effect of depriving a criminal defendant of a conventional entitlement. “ ‘[Wjhen language which is reasonably susceptible of two constructions is used in a penal law ordinarily that construction which is more favorable to the offender will be adopted. [j[] The defendant is entitled to the benefit of every reasonable doubt, whether it arise out of a question of fact, or as to the true interpretation of words or the construction of language used in a statute.’ ” (People v. Davis (1981) 29 Cal.3d 814, 828 [176 Cal.Rptr. 521, 633 P.2d 186], quoting In re Tartar (1959) 52 Cal.2d 250, 256-257 [339 P.2d 553].) A single criminal offense punishable under one statute as a felony or a misdemeanor and under another statute only as a misdemeanor cannot be punished as a felony without depriving the defendant of the doubt as to which punishment the Legislature intended. Refusing to resolve the admitted ambiguity in the law in favor of criminal defendants, the majority instead defers to the charging decision of the district attorney.
The majority incorrectly ascribes to me the view that it is the function of the jury to resolve “ambiguities of legislative intent.” (Maj. opn., ante, at p. 45.) I agree that the resolution of such ambiguity is a judicial function. My point is that the use of ambiguity to justify refiisal to instruct on a lesser related offense indisputably shown by the evidence is an unwarranted abdication of judicial responsibility. The ambiguity is the source of the duty, not the reason it need not be discharged.
II.
The majority says that “where the only dispute presented to jurors is identity or alibi, all the lesser-offense options in the law cannot help them *50resolve it.” (Maj. opn., ante, at p. 47, italics in original.) The error in this claim—which is the fundamental flaw of the entire majority opinion—is the idea that the parameters of the “dispute” in a criminal case are defined solely by the prosecution. If that were true there would be no right to instructions on lesser offenses in the first place, and Geiger would never have been decided. But it is not true.
What was said in People v. Tenorio (1970) 3 Cal.3d 89 [89 Cal.Rptr. 249, 473 P.2d 993] with respect to the right of the court to dismiss allegations of prior convictions over the objection of the prosecutor applies with even greater force to the judicial duty to instruct, which the Legislature has never even attempted to subject to the power of the prosecutor. Tenorio holds that the Legislature cannot grant the prosecutor the unreviewable power to deprive the superior court of the power to strike priors, because “ ‘Constitutional jurisdiction of the court to act cannot be turned on and off at the whimsy of either the district attorney or the Legislature.’ ” (Id., at p. 93, quoting Justice Schauer’s dissenting opinion in People v. Sidener (1962) 58 Cal.2d 645, 652, 654 [25 Cal.Rptr. 697, 375 P.2d 641], which was adopted in Tenorio by a unanimous court.) That is precisely what the majority has done in this case; without even the dubious benefit of the Legislature’s urging, the majority has permitted the charging power of the district attorney to deprive the trial judge of the power to instruct on a lesser related offense, for the illogical reason that the prosecutor, rather than the defendant, has introduced the evidence that would support conviction of such an offense.
The majority says appellant “was necessarily guilty of the greater if guilty of the lesser” (maj. opn., ante, at p. 47, italics in original); and claims I offer “no reason at all why Geiger should apply where its due-process rationale does not.” (Ibid.) The reason, I hope it is clear, is that while appellant may in an abstract sense be “guilty” of both the greater and the lesser offenses, he cannot be convicted of both. Unlike my colleagues, I believe it is the jury, not the prosecutor, that has the right to make that decision. It was deprived of that right in this case by the erroneous refusal of the trial court to instruct on the lesser related offense.
III.
In effect, the majority concludes that appellant’s failure to ask the jury to find him guilty of misdemeanor distribution if it disbelieved his alibi provides a basis for sustaining the trial court’s refusal to instruct on that offense.
Clearly, the only reason appellant did not present to the jury the alternative defense of misdemeanor distribution—ample evidence of that offense *51having been supplied by the prosecution—was that he was erroneously prevented from doing so by the trial court.
In People v. Woods (1991) 226 Cal.App.3d 1037 [277 Cal.Rptr. 269] the defendant was convicted of second degree murder and two counts of attempted murder. One of the questions on appeal was whether the trial court committed prejudicial error by refusing to instruct on assault with a deadly weapon as a lesser related offense of the attempted murder. The Attorney General claimed the trial court correctly refused to give this instruction because the defendant merely attacked the sufficiency of the prosecution’s evidence of actual intent to kill and did not explicitly point out that the evidence amounted to no more than assault with a deadly weapon. In conditionally reversing the conviction of attempted murder, the Court of Appeal rejected this argument. (Id., at p. 1051.) “To expect defense counsel to more fully argue the theory of the lesser related offense after being told the instruction would not be given would be to ask that lawyer to engage in improper conduct. In essence, in making that argument, the defense counsel would be asking the jury to go outside the law as presented by the trial court. In all probability, had he done so the prosecutor would have objected on that very ground. Undoubtedly the judge would have sustained that objection and admonished the jury to disregard any words along these lines which the defense counsel might have uttered before the prosecutor’s objection.” (Ibid.)
There is in this case much stronger evidence of misdemeanor distribution of an imitation controlled substance than there was in Woods of assault with a deadly weapon. Indeed, at the trial in this case, the district attorney explicitly conceded that appellant “certainly knowingly distributed an imitation controlled substance,” and could therefore be convicted under section 11680. The only conceivable reason appellant sought an instruction on that offense was so that he could persuade the jury to find him guilty of it if the jury disbelieved his alibi. The trial court’s erroneous refusal of the instruction prevented appellant from making the argument the majority deems essential. Appellant is thus placed in a “Catch-22.”
The majority contends it would make Geiger's reliance requirement “redundant” if “merely requesting the instruction would show implicit ‘reliance’ on a consistent ‘theory of defense.’ ” (Maj. opn., ante, at p. 46.) This argument ignores the most distinctive feature of this case. While the mere request for an instruction would not ordinarily suffice to show the reliance that Geiger requires it certainly suffices where, as here, it is undisputed that the prosecution's evidence would support a conviction of the lesser offense for which an instruction was requested. This presented an obvious problem *52for the district attorney. His objection to the requested instruction, very different from that offered up by my colleagues, was based on People v. Acevedo (1985) 166 Cal.App.3d 196 [212 Cal.Rptr. 328], in which it was held “that disbelief of all or part of the prosecution case does not require instruction on lesser included offenses . . . .” (Id., at p. 201.) Acevedo has no bearing on the present case. Appellant’s alternative defense does not depend on the jury’s disbelief but its belief of all or part of the prosecution’s case. Permitting appellant to rely on prosecution evidence as an alternative to his alibi defense certainly does not present the problem the Acevedo court was concerned about. The Attorney General concedes as much, as he does not advance the district attorney’s theory on this appeal.
The majority is wrong in saying that “[t]here is no unfairness in asking a defendant who relies on alibi, and wants a lesser-related instruction, to alternatively attack the sufficiency of the evidence supporting the charged offense.” (Maj. opn., ante, p. 47.) The unfairness I perceive does not, as the majority claims, rest “on [my] peculiar premise that Geiger instruction is a remedy for legislative ‘ambiguity’ where given conduct might be punishable as both a misdemeanor and a felony.” (Maj. opn., ante, at p. 47.) My perception of unfairness rests on the firm belief that, as I have said, it is an unjust “Catch-22” to require a defendant to attack the sufficiency of prosecution evidence that he seeks to rely upon.
IV.
The trial court’s refusal to instruct on misdemeanor distribution forced the jury into the all-or-nothing choice that in similar situations has repeatedly been condemned by our Supreme Court. (People v. Ramkeeson (1985) 39 Cal.3d 346, 352 [216 Cal.Rptr. 455, 702 P.2d 613]; People v. Geiger, supra, 35 Cal.3d 510, 519-520; People v. Wickersham (1982) 32 Cal.3d 307, 324 [185 Cal.Rptr. 436, 650 P.2d 311].) Where, as in this case, the jury believed the defendant did something for which he should be punished, without a third choice between conviction on the greater offense and acquittal, there is the substantial risk of an unwarranted conviction which “diminishes the reliability of both the factfinding and the sentencing determination.” (People v. Geiger, supra, at p. 519, citing Beck v. Alabama (1980) 447 U.S. 625, 638, 643 [65 L.Ed.2d 392, 403, 406, 100 S.Ct. 2382].) As pointed out in Geiger, requiring related offense instructions allows “every material issue presented by the evidence” to be determined. (Id., at p. 526.) “Instructions on lesser offenses are required because a procedure which affords the trier of fact no option other than conviction or acquittal when the evidence shows that the defendant is guilty of some crime but not necessarily the one charged, increases the risk that the defendant may be convicted notwithstanding the *53obligation to acquit if guilt is not proven beyond a reasonable doubt. The pressures which create that risk thus affect the reliability of the fact finding process and thereby undermine the reasonable doubt standard.” (Id., at p. 520.)
It is, of course, true that the “third choice” in this case is an offense that is lesser than the charged offense only in the sense that it involves a lesser penalty; that is, however, the only sense that matters.
For the foregoing reasons, I would reverse the conviction.
All statutory references are to the Health and Safety Code unless otherwise indicated.