Lepine

The issue before us is whether in a prosecution for driving a vehicle with a blood alcohol level of 0.10 percent or greater (Veh. Code, § 23152, subd. (b)), the partition or conversion ratio defined by the California Code of Regulations for converting a breath alcohol percentage to a blood alcohol percentage may only be rebutted by the defense demonstrating the defendant had a partition ratio different than that presumed by the code. We conclude the defense is not so restricted and hold general evidence may be offered concerning partition ratio variability.

I

Background

Section 23152, subdivision (b), states in part: “It is unlawful for any person who has 0.10 percent or more, by weight, of alcohol in his or her blood to drive a vehicle. [fl]For purposes of this subdivision, percent, by weight, of alcohol shall be based upon grams of alcohol per 100 milliliters of blood.” Although it is the alcohol content of one’s blood which defines violation of this subdivision, a driver may elect to take a breath or urine test instead of a blood test, for the purpose of determining the alcohol content of his or her blood. (§ 23157, subd. (a).) Thus when a breath or urine sample is…