—Understandably alarmed by the carnage caused by drunk drivers on California’s highways, the Legislature has toughened this state’s laws directed at those who drive a vehicle *894after consuming alcoholic beverages. In interpreting Vehicle Code1 section 23152, subdivision (b) (hereafter section 23152(b)) in this case, however, the majority has gone beyond the stringent prohibitions enacted by the Legislature and has on its own created the new crime of driving with alcohol in one’s breath. This result is achieved only at a serious cost, for it not only tramples the long-standing rule that a court interpreting a criminal statute with two possible meanings must choose the one more favorable to the defendant, but it also invades the Legislature’s exclusive power to create new crimes. Because the law does not permit us to take either action, and because in any event the defendants here were not charged with the majority’s newly created crime of driving with alcohol in the breath, I conclude that the evidence at issue in this appeal was erroneously excluded.
I
In two separate and unrelated cases, the Imperial County District Attorney filed complaints against Donald Bransford and Ralph Maldonado, alleging that each defendant “did willfully and unlawfully, while having .08 percent and more, by weight, of alcohol in his blood, drive a vehicle,” in violation of section 23152(b).
At the time relevant to this case, section 23152(b) provided in its first sentence: “It is unlawful for any person who has 0.08 percent or more, by weight, of alcohol in his or her blood to drive a vehicle.” (Italics added.) The next sentence stated that the “percent, by weight, of alcohol in a person’s blood shall be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.”
The prosecution presented evidence to the jury in each case that the defendant, after arrest, was given a test to measure the amount of alcohol in his breath. As determined by experts, the amount of alcohol contained in 210,000 milliliters (210 liters) of the average person’s breath is equal to the amount of alcohol contained in 100 milliliters of the person’s blood. At each trial, a prosecution expert, relying on this “partition ratio” of 210,000 to 100 (or 2,100 to 1), testified that the breath test showed more than 0.08 percent, by weight, of alcohol in the blood.2
In each case, the defendant asked the trial court, outside the presence of the jury, for permission to cross-examine the prosecution’s expert by asking *895questions designed to show that the partition ratio of 2,100 to 1, even if accurate for the average person, did not accurately measure the amount of alcohol in this defendant’s blood. In each case, the trial court denied the request, and the jury convicted the defendant of violating section 23152 (b).3 In addition, defendant Maldonado was found guilty of the separate offense of driving under the influence of alcohol (Veh. Code, § 23152 subd. (a)), while defendant Bransford was acquitted of that charge.
Both defendants appealed their convictions to the appellate department of the superior court, which consolidated the two cases and certified them to the Court of Appeal. (Cal. Rules of Court, rule 62(c).) The Court of Appeal upheld the convictions.
n
To determine the meaning of section 23152(b), we first examine the statute’s language, read in a commonsense manner. (People v. Broussard (1993) 5 Cal.4th 1067, 1071 [22 Cal.Rptr.2d 278, 856 P.2d 1134]; People v. Morris (1988) 46 Cal.3d 1, 15 [249 Cal.Rptr. 119, 756 P.2d 843].) If the statutory language is ambiguous and susceptible to two plausible interpretations, we must, because this is a criminal statute, adopt the one more favorable to the defendant. (People v. Overstreet (1986) 42 Cal.3d 891, 896 [231 Cal.Rptr. 213, 726 P.2d 1288] (plur. opn.).)
The rule of construction that requires us to construe ambiguities and resolve doubts as to the meaning of criminal statutes in a defendant’s favor is an old and well-established one. (Ex Parte Rosenheim (1890) 83 Cal. 388, 391 [23 P. 372] [“[T]he defendant [in a criminal case] is entitled to the benefit of every reasonable doubt. . . as to the true interpretation of words or the construction of language used in a statute . . . .”]; Harrison v. Vose (1850) 50 U.S. (9 How.) 372, 378 [13 L.Ed.179, 182] [“In the construction of a penal statute, it is well settled, also, that all reasonable doubts concerning its meaning ought to operate in favor of the [defendant].’’].) One early court, describing how criminal statutes “always have been and ever should be” construed, stated the rule this way: “It should be a principle of every criminal code, and certainly belongs to ours, that no person be adjudged guilty of an offence unless it be created and promulgated in terms which leave no reasonable doubt of their meaning. . .. . [A] court has no option where any considerable ambiguity arises on a penal statute, but is bound *896to decide in favour of the party accused.” (The Schooner Enterprise (C.C.D.N.Y. 1810) 8 Fed. 732, 734-735.)
This principle, referred to as the rule of lenity by the United States Supreme Court, is not an arbitrary creation of judges; it arises from two fundamental tenets of our criminal justice system. “First, ‘a fair warning should be given to the world in language that the common world will understand, of what the law intends to do if a certain line is passed. To make the warning fair, so far as possible the line should be clear.’ [Citations.] Second, because of the seriousness of criminal penalties, and because criminal punishment usually represents the moral condemnation of the community, legislatures and not courts should define criminal activity.” (United States v. Bass (1971) 404 U.S. 336, 348 [30 L.Ed.2d 488, 496-497, 92 S.Ct. 515], fn. omitted, quoting McBoyle v. United States (1931) 283 U.S. 25, 27 [75 L.Ed. 816, 818, 51 S.Ct. 340] (per Holmes, J.); accord, Keeler v. Superior Court (1970) 2 Cal.3d 619, 631, 633 [87 Cal.Rptr. 481, 470 P.2d 617, 40 A.L.R.3d 420].)
As this court observed nearly 25 years ago: “[Cjourts cannot go so far as to create an offense by enlarging a statute, by inserting or deleting words, or by giving the terms used false or unusual meanings. [Citation.] Penal statutes will not be made to reach beyond their plain intent; they include only those offenses coming clearly within the import of their language. [Citation.] Indeed, ‘Constructive crimes—crimes built up by courts with the aid of inference, implication, and strained interpretation—are repugnant to the spirit and letter of English and American criminal law.’ [Citation.]” (Keeler v. Superior Court, supra, 2 Cal.3d at p. 632.)
These rules of construction make short work of the task of interpreting section 23152(b). The first sentence of section 23152(b) describes the conduct proscribed: “It is unlawful for any person who has 0.08 percent or more, by weight, of alcohol in his or her blood to drive a vehicle.” In unambiguous language, the statute prohibits anyone having at least 0.08 percent of alcohol in the blood from driving a car. Nothing in this statutory language prohibits driving with a given quantity of alcohol in the breath.
At the time of defendants’ arrests, the statute’s second sentence provided: “For purposes of this subdivision, percent, by weight, of alcohol in a person’s blood shall be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.” (Stats. 1990, ch. 708, § 1, *897italics added.)4 As is true of the statute’s first sentence, nothing in the second sentence expressly forbids driving with alcohol in the breath. The second sentence does not purport to make any conduct unlawful, in contrast to the first sentence, which begins “It is unlawful . . . .’’On its face, the second sentence—by stating that percent of blood alcohol by weight “shall be based upon” either blood-alcohol or breath-alcohol measurements—merely sets forth two alternatives by which the prosecution may prove the crime of driving with 0.08 percent, by weight, of alcohol in one’s blood. The prosecution can establish the defendant’s blood-alcohol level either by showing the grams of alcohol per 100 milliliters of the defendant’s blood or circumstantially by showing the grams of alcohol per 210 liters of the defendant’s breath.
Thus, the plain language of section 23152(b) expressly prohibits only driving with alcohol in the blood, and not driving with alcohol in the breath. The majority acknowledges that it is “possible” to construe section 23152(b) as prohibiting only the act of driving with alcohol in one’s blood. (Maj. opn., ante, at p. 890.)
The majority nonetheless relies on the second sentence of section 23152(b) to create an ambiguity in the meaning of the otherwise unambiguous phrase “alcohol in his or her blood” used in the first sentence. The majority asserts that the second sentence provides “two distinct definitions” of alcohol in a person’s blood and under the second “definition” prohibits “the act of driving with 0.08 percent or more of blood alcohol as defined by grams of alcohol in 210 liters of breath.” (Maj. opn., ante, at p. 890, original italics.) In doing so, the majority mischaracterizes the language of the second sentence, which nowhere purports to define the term “alcohol in [the] blood” used in the first sentence and does not state that alcohol in the blood is “defined by” alcohol in the breath.
In the majority’s view, its reading of the second sentence makes the phrase “alcohol in his or her blood,” as it is used in the first sentence to describe the conduct prohibited by section 23152(b), ambiguous and capable of meaning either alcohol in one’s blood or alcohol in one’s breath. The majority concludes from this that “the Legislature intended the statute to criminalize the act of driving either with the specified blood-alcohol level or with the specified breath-alcohol level.” (Maj. opn., ante, at p. 890.) The majority then supports this conclusion by invoking the legislative history of section 23152(b).
*898It is irrelevant, however, whether the majority is correct that the second sentence of section 23152(b) renders the first sentence ambiguous and makes the majority’s interpretation a possible construction. Even assuming that a legitimate ambiguity exists, because the majority’s construction is the harsher one, the rule of lenity forbids us from adopting it. “[Wjhere there is ambiguity in a criminal statute, doubts are resolved in favor of the defendant.” (United States v. Bass, supra, 404 U.S. at p. 348 [30 L.Ed.2d at p. 497].) Because driving with alcohol in the blood is the only crime clearly within the language of section 23152(b), it is the only crime the Legislature created in that statute. (See Keeler v. Superior Court, supra, 2 Cal.3d at p. 632.) We have “no option” in the matter and our task of interpretation should end here. (See The Schooner Enterprise, supra, 8 Fed. at p. 735.)
Nevertheless, the majority, contrary to the settled rule of construction described above, adopts the construction unfavorable to defendants and holds that section 23152 creates two separate offenses—driving with alcohol in the blood, and driving with alcohol in the breath. By its suggestion that in interpreting penal statutes courts should choose the interpretation that will “increase the likelihood of convict[ion],” cause “fewer legal issues [to] arise,” and make defendants “less likely to contest the charge,” (maj. opn., ante, at pp. 891-892), the majority appears to be applying a completely unprecedented “rule of harshness” in interpreting section 23152(b).
Long ago, Chief Justice Marshall rejected in the strongest terms the proposition that a court should choose the harsher of two interpretations of a criminal statute in order to make the statute more effective at eradicating the evil it is aimed at: “The rule that penal laws are to be construed strictly, is perhaps not much less old than construction itself. It is founded on the tenderness of the law for the rights of individuals; and on the plain principle, that the power of punishment is vested in the legislative, not in the judicial department. It is the legislature, not the court, which is to define a crime, and ordain its punishment. [H ... It would be dangerous, indeed, to carry the principle, that a case which is within the reason or mischief of a statute, is within its provisions, so far as to punish a crime not enumerated in the statute, because it is of equal atrocity, or of kindred character, with those which are enumerated.” (United States v. Wiltberger (1820) 18 U.S. (5 Wheat.) 76, 95-96 [5 L.Ed. 37, 42].)5
*899Even if the rule of lenity did not exist, in my view the majority’s interpretation of the statute is an implausible rendering of what the Legislature intended here. In section 23152(b), only the first sentence purports to make any conduct unlawful, and the only conduct it makes unlawful is driving with alcohol in the blood. The second sentence does not purport to define the term “alcohol in the blood” to mean as well alcohol in the breath. Instead of using the word “define” or some equivalent term, the second sentence uses the construction “shall be based upon” to describe the relationship between alcohol in the blood and alcohol in the breath. A base is something that supports or provides the foundation for something else, as, for example, a block supports a column or evidence supports a conclusion. As used in the second sentence of section 23152(b), the phrase “shall be based upon” does not suggest a definitional relationship of equivalence or interchangeability between the two matters it connects (here, blood alcohol as percent by weight and breath alcohol), as the majority’s reading proposes. To the contrary, the words “percent, by weight, of alcohol in a person’s blood shall be based upon . . . grams of alcohol per 210 liters of breath” suggest that existence of a given amount of blood alcohol is a conclusion inferentially derived by some intermediate process of reasoning or deduction from the existence of alcohol in the breath. Had the second sentence been intended as a definition, it would have likely used the words “means” or “is defined as,” instead of “shall be based upon.”
Thus, the more plausible construction of section 23152(b) is that it creates a permissive presumption, permitting but not requiring the jury to find that a person who has 0.08 grams of alcohol per 210 liters of the breath has 0.08 percent, by weight, of alcohol in the blood. Under this construction, anyone driving with 0.08 grams of alcohol in 210 liters of the breath could thereby be presumed to also have 0.08 percent, by weight, of alcohol in the blood, and therefore to have violated section 23152(b). In turn, the defendant could attempt to rebut the inference that the presumption gives rise to, by introducing evidence of the type that was excluded here.6 In my view, interpreting the second sentence of section 23152(b) as creating this rebuttable presumption is the most reasonable interpretation of the statutory language, as well as the one that is in accord with the rule of lenity.7
*900III
Even if, as the majority holds, the Legislature did make it an offense to drive with a certain percentage of alcohol in one’s breath, that offense is irrelevant here because neither defendant was so charged. In each case, the complaint alleged that the defendant “did willfully and unlawfully, while having .08 percent and more, by weight, of alcohol in his blood, drive a vehicle.” (Italics added.) In each case, the jury instructions made no mention of driving with alcohol in the defendant’s breath. Rather, in each case the trial court instructed the jury: “Any person who drives a vehicle with 0.08 percent or more, by weight, of alcohol in his blood, is guilty of a misdemeanor.” (Italics added.) And in each case the verdict form made reference only to the amount of alcohol in the defendant’s blood.8
In short, the complaints, the jury instructions, and the verdicts all show that both defendants were charged with and convicted of driving with alcohol in their blood, and not the crime of alcohol in the breath that the majority has discovered lurking in the statute. Accordingly, the majority’s *901conclusion—that evidence of the relationship between breath alcohol and blood alcohol is irrelevant to its new crime of driving with alcohol in the breath—has no application to these defendants because they were not charged with or convicted of that crime.
IV
In each case, the trial court erred in excluding the “partition ratio” evidence of the relationship between breath alcohol and blood alcohol that the defendants sought to introduce. Because section 23152(b) does not criminalize driving with alcohol in the breath, and because in any event both defendants were only charged with driving with alcohol in the blood, the prosecution was required to prove that each defendant had a blood-alcohol level of 0.08 percent or more, by weight. The prosecution attempted to prove circumstantially how much alcohol was in each defendant’s blood by means of evidence showing how much alcohol was in his breath, and expert evidence calculating the blood-alcohol level of each defendant by applying a partition ratio of 2,100 to 1 to the breath-alcohol level of each defendant.
Each defendant sought to refute this inference of his blood-alcohol level by introducing evidence, through the prosecution’s experts, of possible variations between the average partition ratio and the partition ratio of the defendants. It is undisputed that the correlation between blood-alcohol levels and breath-alcohol levels can vary in different individuals, and that the partition ratio of 2,100 to 1 is only an average value for that correlation. Here, the defendants’ partition ratio evidence, by attempting to show that the partition ratio of 2,100 to 1 did not accurately establish the quantity of alcohol in each defendant’s blood, was relevant to disproving the prosecution’s theory as to the relationship between alcohol in the defendants’ breath and alcohol in their blood. In each case, the trial court erred in excluding this evidence.
The question in each case remains whether the error was prejudicial. With regard to defendant Maldonado, the appellate record does not show the results of the test that measured the alcoholic content of his breath. Thus, it is impossible to determine the effect of the trial court’s erroneous ruling. It may be that the quantity of alcohol in Maldonado’s breath was so great that the expert would have testified that, even applying a partition ratio far more favorable to Maldonado, his blood-alcohol content nevertheless exceeded 0.08 percent. Because Maldonado has failed to satisfy his burden of producing an adequate record from which this court can assess whether the trial court’s error was prejudicial, I would affirm his conviction of violating section 23152(b).
With respect to defendant Bransford, the prosecution’s expert witness testified that the breath test showed a blood-alcohol concentration of 0.09 *902percent, close to the legal limit of 0.08 percent. In my view, if the trial court had permitted Bransford to cross-examine the prosecution’s expert witness regarding the accuracy of the partition ratio, there is a reasonable probability that the jury would have entertained a reasonable doubt that the alcohol in his blood equaled or exceeded 0.08 percent. (See People v. Watson (1956) 46 Cal.2d 818, 836 [299 P.2d 243].)9 I would therefore reverse defendant Bransford’s conviction of violating section 23152(b).
V
Conclusion
“The temptation to stretch the law to fit the evil is an ancient one, and it must be resisted.” (Moskal v. United States (1990) 498 U.S. 103, 132 [112 L.Ed.2d 449, 473, 111 S.Ct. 461] (dis. opn. of Scalia, J.).) We all share a desire to drive our cars free from the fear of injury or death at the hands of a drunk driver. A statute criminalizing driving with alcohol in the breath may well “promote[] the state’s interest in reducing the danger to the public caused by those who drink and drive.” (Maj. opn., ante, p. 891].)
As a court, however, our task is to apply the laws that the Legislature has enacted, not those it could have enacted but did not. Thus, no matter how tempting, this court cannot create a new crime of driving with a given amount of alcohol in the breath, by stretching the language of section 23152(b) “to fit the evil” of drunk driving, as the majority has done. It is up to the Legislature to make such conduct unlawful, doing so in terms that plainly and unmistakably give fair notice of the prohibited behavior. (See United States v. Bass, supra, 404 U.S. at pp. 348-349 [30 L.Ed.2d at pp. 496-498]; Keeler v. Superior Court, supra, 2 Cal.3d at pp. 632-633.) The Legislature has not yet done so. Accordingly, I would reverse the judgment of the Court of Appeal as to defendant Bransford. With respect to defendant Maldonado, he failed to show prejudice from the error in his case; therefore, I would affirm the Court of Appeal’s judgment as to him.
Appellants’ petition for a rehearing was denied January 19, 1995. Kennard, J., was of the opinion that the petition should be granted.
Unless otherwise stated, all subsequent statutory references are to the Vehicle Code.
In the case of defendant Bransford, the expert concluded that the breath test showed a blood-alcohol concentration of 0.09 percent, close to the legal limit of 0.08 percent. With respect to defendant Maldonado, the record does not disclose the exact results of the breath test.
The appellate record contains no transcript of either trial, only settled statements. These reveal little about the evidence admitted at trial; each settled statement merely shows the trial court denied the defendant’s request to cross-examine the expert on the accuracy of the partition ratio.
The Legislature later amended the second sentence of section 23152(b) to read: “For purposes of this article and Section 34501.16, percent, by weight, of alcohol in a person’s blood is based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.” (Stats. 1992, ch. 974, § 16, italics added.)
On occasion, we have construed facially ambiguous statutes adversely to criminal defendants when to do otherwise “ ‘ “ ‘would result in absurd consequences which the Legislature did not intend.’ ” ’ ’’ (People v. Broussard, supra, 5 Cal.4th at p. 1071; People v. Pieters (1991) 52 Cal.3d 894, 898-901 [276 Cal.Rptr. 918, 802 P.2d 420].) In this case, however, the majority does not contend that construing section 23152(b) favorably to defendants would result in “absurd consequences.”
As explained in People v. Milham (1984) 159 Cal.App.3d 487, 503 [205 Cal.Rptr. 688], “A permissive presumption allows—but does not require—the trier of fact to infer the ultimate fact from proof by the prosecutor of the ‘basic’ fact, and places no burden of any kind on defendant.”
In addition, the differences between the statute enacted by our Legislature and the model drunk driving statute of the Uniform Vehicle Code, which unambiguously does criminalize driving with alcohol in one’s breath, also show that section 23152(b) is not a statute that criminalizes driving with alcohol in the breath. The Uniform Vehicle Code prohibits a person *900from driving a vehicle when “The alcohol concentration in such person’s blood or breath is 0.08 or more . . . .” (U. Veh. Code (1992 rev.) § 11-902, subd. (a)(1), italics added.) By contrast, the prohibitory language of section 21532(b) prohibits only driving with “alcohol in [the] blood.” Moreover, in discussing the measurement of alcohol in the blood and the breath, the Uniform Vehicle Code provides that “Alcohol concentration shall mean either grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.” (U. Veh. Code, supra, § 11-903, subd. (a)(5), italics added.) By contrast, the second sentence of section 21352(b) is cast in terms of “alcohol in [the] blood,” not “alcohol concentration” generally, and uses the phrase “shall be based upon,” rather than the definitional phrase “shall mean.”
The Wisconsin and Illinois statutes referred to by the majority (maj. opn., ante, at p. 892 & fn. 9) also are statutes that, like the Uniform Vehicle Code, expressly create a separate offense of driving with alcohol in the breath. (State v. McManus (1989) 152 Wis.2d 113 [447 N.W.2d 654, 657] [“(1) No person may drive or operate a motor vehicle while: [ ] HD (b) The person has a blood alcohol concentration of 0.1% or more by weight of alcohol in the person’s blood or 0.1 grams or more of alcohol in 210 liters of that person’s breath.”]; People v. Capporelli (1986) 148 Ill.App.3d 1048 [103 Ill.Dec. 864, 502 N.E.2d 11, 14] [“ ‘(a) A person shall not drive or be in actual physical control of any vehicle within this State while: (1) The alcohol concentration in such person’s blood or breath is 0.10 or more .... [^Q ... 5. Alcohol concentration shall mean either grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.’ ”].) Unlike those states, our Legislature has not enacted a similar statute.
In defendant Bransford’s case, the verdict read: “We, the jury in the above-entitled cause, find the defendant Donald Edward Bransford Guilty of the offense charged, to wit: Count 2, in violation of Sec. 23152b, of the Vehicle Code, a misdemeanor, said defendant did willfully and unlawfully, while having .08 percent or more, by weight, of alcohol in his blood, drive a vehicle.” In defendant Maldonado’s case, the verdict read: “We, the jury in the above-entitled cause, find the defendant Ralph Maldonado Guilty of the offense charged, to wit: Ct II Driving With .08% or More, Alcohol in His Blood, in Violation of 23152b of the Vehicle Code.”
It is arguable that by restricting defendant Bransford’s cross-examination of the expert witness, the trial court violated his federal constitutional right to confront the witnesses against him, and that the effect of the trial court’s error should be measured by the “harmless beyond a reasonable doubt” standard set forth in Chapman v. California (1967) 386 U.S. 18 [17 L.Ed.2d 705, 87 S.Ct. 824, 24 A.L.R.3d 1065]. Because I conclude that the error was prejudicial in any event, I do not reach this question.