Opinion ID: 2635209
Heading Depth: 2
Heading Rank: 3

Heading: Admissibility of Partition Ratio Evidence in Generic DUI Cases

Text: Despite our holding in Bransford that partition ratio evidence is inadmissible in per se DUI cases, defendant argues partition ratio variability evidence should be admissible in generic DUI cases to rebut the presumption that a person who produces a certain breath result is actually under the influence of alcohol. (§§ 23152(a), 23610(a)(3).) This issue was not presented in Bransford, and we specifically declined to consider it. ( Bransford, supra, 8 Cal.4th at p. 893, fn. 10.) Defendant's claim does involve the same statutory language we interpreted in Bransford : Percent, by weight, of alcohol in the person's blood shall be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath. (§ 23610(b); see Bransford, at p. 890, quoting § 23152(b).) However, in Bransford this language was used in the definition of a criminal offense. Here, it is part of a rebuttable presumption. The question is whether a defendant who has a blood-alcohol concentration of 0.08 percent or more measured by breath is entitled to rebut the presumption that he was under the influence in a section 23152(a) case by introducing evidence that use of a 2,100-to-1 partition ratio may have produced an inaccurate measure of his blood alcohol. (2) The Legislature passed section 23152(b) to facilitate the prosecution of drunk drivers. The creation of a per se DUI offense did away with the need to prove the defendant was actually impaired. However, impairment must still be proven for a charge of generic DUI under section 23152(a). In a generic DUI case, section 23610 creates a rebuttable presumption that the defendant was under the influence of alcohol if a chemical test measures his blood-alcohol concentration at 0.08 percent or higher. As relevant here, section 23610 states: (a) Upon the trial of any criminal action, or preliminary proceeding in a criminal action, arising out of acts alleged to have been committed by any person while driving a vehicle while under the influence of an alcoholic beverage in violation of subdivision (a) of Section 23152 or subdivision (a) of Section 23153, the amount of alcohol in the person's blood at the time of the test as shown by chemical analysis of that person's blood, breath, or urine shall give rise to the following presumptions affecting the burden of proof: [¶] . . . [¶] (3) If there was at that time 0.08 percent or more, by weight, of alcohol in the person's blood, it shall be presumed that the person was under the influence of an alcoholic beverage at the time of the alleged offense. [9] (b) Percent, by weight, of alcohol in the person's blood shall be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath. (c) This section shall not be construed as limiting the introduction of any other competent evidence bearing upon the question of whether the person ingested any alcoholic beverage or was under the influence of an alcoholic beverage at the time of the alleged offense. (3) Although section 23610 applies to chemical testing of the driver's blood, breath, or urine, the presumption of intoxication arises only if the testing shows the presence of 0.08 percent or more of alcohol in the driver's blood. (§ 23610(a)(3).) The statute is not written to invoke a presumption based on a certain blood result or breath result; it is framed in terms of blood alcohol only. Thus, if the prosecution is relying on the result of a breath test, the breath result must be converted into a blood-alcohol equivalent for the section 23610 presumption to apply. Subdivision (b) sets this conversion factor at a ratio of 210 liters of breath to 100 milliliters of blood. The logic of the presumption proceeds as follows. The Legislature has concluded that most people with a blood-alcohol concentration at or above 0.08 percent are too impaired to operate a vehicle safely. Breath tests are a convenient way to measure a suspect's alcohol consumption, and they can be converted into an equivalent blood-alcohol level by applying a mathematical ratio. A conversion ratio of 2,100 to 1 is a safe standard to use because, for most people, it will produce an accurate or slightly low measure of alcohol in the blood. (See, e.g., People v. Lepine, supra, 215 Cal.App.3d at p. 94; Downie, supra, 569 A.2d at p. 247; Brayman, supra, 751 P.2d at p. 300.) Thus, if a driver's breath test shows a converted blood-alcohol level of 0.08 percent or more, the measurement is generally accurate and may fairly be used to prove the driver was actually under the influence, as the generic DUI statute requires. Other evidence of actual impairment may include the driver's appearance, an odor of alcohol, slurred speech, impaired motor skills, slowed or erratic mental processing, and impaired memory or judgment. Conversely, absence of these manifestations may indicate that the driver was not impaired. (4) With regard to the inference to be drawn from a breath result, the question of whether a defendant's converted blood-alcohol level is accurate depends upon the validity of the 2,100-to-1 partition ratio. If the defendant's own partition ratio is the same as or higher than this standard ratio, his converted blood-alcohol result is valid or skewed in his favor. If, however, the defendant's own partition ratio at the time of testing is lower than the standard ratio, conversion of the breath result using the statutory formula produces an artificially high measure of his blood alcohol. Evidence that a defendant has a comparatively low partition ratio would thus tend to show that a blood-alcohol concentration calculated with the standard 2,100-to-1 ratio overstates the actual amount of alcohol in his blood. For someone with an extremely low ratio of 1,100 to 1, for example, use of the 2,100-to-1 partition ratio would overstate blood-alcohol content by almost 50 percent. (See State v. Burling (1987) 224 Neb. 725 [400 N.W.2d 872, 876-877].) [10] Evidence showing the defendant had a low partition ratio, and thus a lower concentration of blood alcohol than was reported, could also support an inference that he was not under the influence in violation of the generic DUI law. In addition, evidence about the variability of partition ratios in the general population is relevant to raise a reasonable doubt about the accuracy of a defendant's converted blood-alcohol level. Because partition ratios vary among individuals and the 2,100-to-1 ratio used by breath-testing machines is based on an average, there is a possibility that the blood-alcohol level such a machine produces for a given defendant is inaccurate. (5) The People contend the Legislature rendered partition ratio evidence irrelevant when it amended section 23610, subdivision (b) to state that blood-alcohol percentages shall be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath. According to the People's reasoning, because the Legislature has placed a partition ratio in section 23610, no evidence can be offered to contradict or question that ratio in a particular case. Evidence that defendant may have a different ratio is irrelevant, the People assert, because the Legislature has spoken and established 2,100 to 1 as the ratio to be used in every case. Our reasoning was similar when we construed the partition ratio amendments to section 23152(b) in Bransford, supra, 8 Cal.4th at page 892, but the People's attempt to apply Bransford here overlooks an important difference in context. As noted, in Bransford, we were construing language in a statute that defines an offense. Section 23512(b) makes it a crime to drive with a blood-alcohol content of 0.08 percent or more as measured in grams of alcohol per 100 milliliters of blood or per 210 liters of breath. The crime itself is defined in terms of a prohibited blood or breath result. Here, we are considering language in a statute that describes a rebuttable presumption. Section 23610 permits, but does not require, the jury to infer that the defendant was under the influence if he had a blood-alcohol level of 0.08 percent or more. (See People v. Milham (1984) 159 Cal.App.3d 487, 505 [205 Cal.Rptr. 688]; see also CALJIC No. 12.61; CALCRIM No. 2110.) Although section 23610, subdivision (b) incorporates the same conversion factor for breath test results as appears in section 23152, subdivision (b), here this factor is not part of the definition of an offense and, like the rest of the presumption, it is rebuttable. (6) Moreover, section 23610 specifically mandates that it shall not be construed as limiting the introduction of any other competent evidence bearing upon the question of whether the person ingested any alcoholic beverage or was under the influence of an alcoholic beverage at the time of the alleged offense. (§ 23610, subd. (c).) Thus, even in light of the presumption, a defendant charged under the generic 23152(a) provision is entitled to offer other competent evidence relevant to whether he was actually under the influence of alcohol. [11] (7) Competent evidence that the 2,100-to-1 ratio does not accurately reflect the partition ratio for all people, or that the defendant's partition ratio may have been lower, is relevant to this question. `Relevant evidence' means evidence ... having any tendency in reason to prove or disprove any disputed fact that is of consequence to the determination of the action. (Evid. Code, § 210.) The central disputed fact in a generic DUI prosecution is whether the defendant was under the influence of alcohol while driving. The chemical test result is circumstantial evidence that supports an inference regarding that disputed fact. (8) Specifically, when a defendant's breath test result is equivalent to 0.08 percent or more of blood alcohol, section 23610 permits the jury to infer he was indeed under the influence of alcohol. The defendant is entitled to challenge this inference and can do so by, among other things, raising a reasonable doubt as to whether the test result was an accurate measure of his blood-alcohol level. Evidence casting doubt on the accuracy of the breath-to-blood conversion ratio is just as relevant as other evidence rebutting the presumption of intoxication from a breath test result, such as evidence that the defendant had a high tolerance for alcohol or performed well in field sobriety testing. (9) Accordingly, we hold that evidence about partition ratio variability is relevant in generic DUI cases to rebut the presumption of intoxication in section 23610. Although the Court of Appeal distinguished between general and personal partition ratio evidence, concluding only the latter is potentially admissible, this distinction does not survive close scrutiny. Both types of evidence challenge the accuracy of a defendant's reported blood-alcohol level, and therefore both can be used to support an inference that, despite a high breath test result, the defendant was not under the influence. Although the inference is less direct when the evidence is not tied to the defendant, and concerns only variability of partition ratios in the population at large, indirectness alone is not a reason to exclude evidence that is logically relevant to a defense. We do agree with the Court of Appeal, however, that partition ratio evidence may not be used to negate the basic fact triggering the section 23610 presumption, and thereby defeat operation of the presumption itself. Because section 23610 expressly incorporates a 2,100-to-1 partition ratio, defendant may not argue the presumption does not apply because a different ratio should have been used. The result of the statutorily mandated test remains admissible, and the jury is still properly instructed on the presumption. Defense evidence is relevant to rebut the presumption that defendant was intoxicated, but not to remove the presumption altogether. Our decision is in accord with those of the two other state courts that have discussed the admissibility of partition ratio evidence in generic DUI cases. In State v. Hanks (2001) 172 Vt. 93, 96 [772 A.2d 1087, 1089] ( Hanks ), the Vermont Supreme Court considered the effect of a statute that defined alcohol concentration for purposes of the state's DUI laws to mean grams of alcohol per 100 milliliters of blood or per 210 liters of breath. The defendant in Hanks conceded this statute may have made evidence about partition ratio variability inadmissible in cases alleging a violation of the state's per se DUI law, but he argued such evidence was still relevant in cases alleging the defendant drove under the influence of intoxicating liquor in violation of the generic DUI law. ( Id., 772 A.2d at pp. 1088, 1091.) The Vermont Supreme Court agreed. ( Id. at p. 1091.) The court observed that  any evidence raising a doubt as to [the] defendant's condition, which is the ultimate question in a generic DWI prosecution . . . is relevant and admissible. ( Id. at p. 1092, italics added, citation omitted.) Like California, Vermont has a statutory presumption that permits the jury to infer a person with a blood-alcohol concentration of 0.08 percent or more was under the influence of alcohol at the time of the offense. (23 Vt. Stat. Ann. § 1204, subd. (a)(2); see Hanks, at p. 1088.) The Hanks court explained that evidence about partition ratio variability is relevant to rebut this inference because it could cast doubt on the accuracy of the breath test result as an indicator of the defendant's impairment. ( Hanks, at p. 1092.) Finally, the court observed, where the defendant is charged with driving while under the influence rather than driving with an alcohol concentration exceeding the statutory limit, admitting scientifically accepted evidence concerning the variability of partition ratios will not negate a statutory offense or even an element of a statutory offense; rather, it will merely allow defendant to challenge the permissive inference and the State's charge that he was impaired. ( Id. at pp. 1092-1093.) An Arizona appellate court considered the same question, in light of similar statutes, and concluded evidence about partition ratio variability is not relevant to a prosecution for per se DUI, but may be relevant to a prosecution for traditional DUI if, in the latter instance, the State introduces evidence of the defendant's breath alcohol level to support conviction. ( Guthrie v. Jones (Ct.App. 2002) 202 Ariz. 273, 274 [43 P.3d 601, 602] ( Guthrie ).) The court reasoned that when the prosecution relies on a breath test result to invoke Arizona's statutory presumption that the defendant was under the influence of alcohol (Ariz. Rev. Stat. § 28-1381, subd. (G)), partition ratio evidence casting doubt on that presumption is relevant and admissible. ( Guthrie, at p. 604.) The Guthrie court relied in part on statutory language similar to our section 23610, subdivision (c), concluding that the statute does not limit the introduction of any other competent evidence bearing on the question of whether or not the defendant was under the influence of intoxicating liquor. (Ariz. Rev. Stat. § 28-1381, subd. (H); see Guthrie, at p. 604.) (10) We reach the same conclusion as the Vermont and Arizona courts. If the defendant in a section 23152(a) case offers competent evidence showing that the use of a 2,100-to-1 conversion ratio may have yielded an inaccurate representation of his blood-alcohol level, introduction of this evidence is permissible. In light of this decision, we need not consider whether a contrary interpretation of section 23610 would raise constitutional concerns. (See Santa Clara County Local Transportation Authority v. Guardino (1995) 11 Cal.4th 220, 230 [45 Cal.Rptr.2d 207, 902 P.2d 225] [the court will not decide constitutional questions where other grounds are available and dispositive]; see also Lyng v. Northwest Indian Cemetery Prot. Assn. (1988) 485 U.S. 439, 445 [99 L.Ed.2d 534, 108 S.Ct. 1319].) Naturally, the proffered evidence must still satisfy standards of competence and all other applicable evidentiary requirements. We do not here consider how a party might establish partition ratio variability in general or in regard to an individual. In particular, we express no opinion as to whether evidence of an individual's personal partition ratio has gained sufficient acceptance in the scientific community to be admissible. (See People v. Kelly (1976) 17 Cal.3d 24, 30-32 [130 Cal.Rptr. 144, 549 P.2d 1240].) In addition, like all other evidence, partition ratio evidence must be timely offered. Here, defendant attempted to introduce this evidence only after both sides had rested. His motion to reopen was one addressed to the court's sound discretion. ( People v. Jones (2003) 30 Cal.4th 1084, 1110 [135 Cal.Rptr.2d 370, 70 P.3d 359]; People v. Marshall (1996) 13 Cal.4th 799, 836 [55 Cal.Rptr.2d 347, 919 P.2d 1280].) We need not discuss this procedural question further. Like the Court of Appeal, we may assume that defendant could have made an adequate offer of proof, to be presented by a competent witness, and that the trial court would have allowed him to reopen. Nevertheless, defendant is not entitled to a reversal here, because any error in excluding the partition ratio evidence was harmless. (11) As a general matter, the `[a]pplication of the ordinary rules of evidence . . . does not impermissibly infringe on a defendant's right to present a defense.' [Citations.] ( People v. Fudge (1994) 7 Cal.4th 1075, 1102-1103 [31 Cal.Rptr.2d 321, 875 P.2d 36].) Because the trial court merely rejected some evidence concerning a defense, and did not preclude defendant from presenting a defense, any error is one of state law and is properly reviewed under People v. Watson, supra, 46 Cal.2d at page 836. ( People v. Fudge , at p. 1103.) Having examined all the evidence, we conclude it is not reasonably probable defendant would have achieved a more favorable result absent the exclusion of partition ratio evidence. The question for the jury was whether defendant was under the influence of alcohol when he drove through two red lights. Defendant was stopped at 11:00 p.m. When asked to produce his driver's license, he initially could not find it. Asked why he ran the lights, defendant replied, at first, that he was chasing someone who had threatened him with a gun. Later, he said he was looking for his wife, or that his wife was following right behind him. The arresting officer saw no one else around. Defendant's eyes were watery and bloodshot, his speech was slurred, and a strong odor of alcohol came from the interior of his car and from his person. His face was flushed and he had difficulty answering questions. When he got out of his car, he leaned on the vehicle for support as he made his way to the sidewalk. Defendant said he had consumed one beer and had taken medication that morning for diabetes; however, no evidence offered at trial showed defendant was diabetic. Defendant failed every one of the field sobriety tests he tried to perform. A preliminary alcohol screening test given at the scene showed the presence of alcohol in his breath. Based on defendant's driving, appearance, and performance on the field sobriety tests, the arresting officer formed an opinion that defendant was impaired due to the influence of alcohol. In addition to this significant evidence of defendant's intoxication, the jury's verdict also indicates that the admission of partition ratio evidence was not reasonably likely to have produced a more favorable result. (See People v. Watson, supra, 46 Cal.2d at p. 836.) Although they found him guilty of generic DUI, the jury could not agree whether defendant was also guilty of per se DUI. They reported an unspecified split of five to seven on this issue. Thus, even without partition ratio evidence, nearly half the jury rejected the accuracy of defendant's breath test result and declined to find that he had exceeded the legal limit of 0.08 percent blood alcohol. Nevertheless, all jurors believed defendant was under the influence for purposes of section 23152(a). It is difficult to imagine that the jurors who rejected defendant's breath result in considering the per se DUI charge would have relied on this result, and the section 23610 presumption, to convict him of the generic DUI charge.