Driving Under the Influence Alcohol Drugs Laws (Veh. Code, §§ 23152, 23153)

The statute just read to you uses the term “under the influence.” A driver is not necessarily “under the influence” just because the driver has consumed some alcohol [or drugs]. A driver is “under the influence” when the driver has consumed an amount of alcohol [or drugs] that impairs the driver’s ability to drive in a reasonably careful manner.

• Driving Under the Influence of Alcohol or Drugs. Vehicle Code sections 23152(a), 23153(a).
  
  
• Veh. Code, § 23152, subd. (b), criminalizes the act of driving with either the specified blood-alcohol level or the specified breath-alcohol level. The statute as amended in 1990 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. The amended statute renders irrelevant consideration of matters such as partition ratio variability, because the revised statute defines the offense without regard to such ratios. It follows that expert evidence concerning partition ratio variability is properly excluded in trials under the amended per se statute.  People v. Vangelder, 58 Cal. 4th 1
• “All of the decided cases on the subject recognize that it is negligence as a matter of law to drive a vehicle upon a public highway while in an intoxicated condition.” (Zamucen v. Crocker (1957) 149 Cal.App.2d 312, 316 [308 P.2d 384], internal citations omitted.)
  
  
• The term “under the influence” was first defined in People v. Dingle (1922) 56 Cal.App. 445, 449 [205 P. 705], as follows: “[I]f intoxicating liquor has so far affected the nervous system, brain, or muscles of the driver of an automobile as to impair, to an appreciable degree, his ability to operate his car in the manner that an ordinarily prudent and cautious man, in the full possession of his faculties, using reasonable care, would operate or drive a similar vehicle under like conditions, then such driver is ‘under the influence of intoxicating liquor’ within the meaning of the statute.”
  
  
• “One is not necessarily under the influence of intoxicating liquor as the result of taking one or more drinks. The circumstances and effect must be considered; whether or not a person was under the influence of intoxicating liquor at a certain time is a question of fact for the jury to decide.” (Pittman v. Boiven (1967) 249 Cal.App.2d 207, 217 [57 Cal.Rptr. 319].)
  
  

• Driving while “under the influence” under Vehicle Code sections 23152 and 23153 is not the same as “being under the influence” of a controlled substance under Health and Safety Code section 11550. Under the Vehicle Code provisions, “the defendant’s ability to drive must actually be impaired,” while the Health and Safety Code provision is violated as soon as the influence is present “in any detectable manner.” (People v. Enriquez (1996) 42 Cal.App.4th 661, 665 [49 Cal.Rptr.2d 710].)
  
  
• Courts have also distinguished the “under the influence” standard from the “obvious intoxication” standard used in Business and Professions Code section 25602.1. (Jones v. Toyota Motor Co. (1988) 198 Cal.App.3d 364, 368 [243 Cal.Rptr. 611]: “ ‘Under the influence’ is defined by a person’s capability to drive safely, whereas ‘obvious intoxication’ is defined by a person’s appearance.”)
• Driving Under the Influence, Blood Alcohol & Field Sobriety Testing
  By statute, if a chemical test within three hours of driving measures a driver’s blood alcohol at 0.08 percent or more, the driver is presumed to have been driving under the influence of alcohol. Veh. Code, § 23610, subd. (a)(3).  People v. McNeal, 46 Cal. 4th 1183.
  
  
• For purposes of the per se driving under the influence offense and the presumption of intoxication, the percentage of alcohol in a person’s blood is to be based upon grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath. Veh. Code, § 23152, subd. (b); former Veh. Code, § 23155, subd. (b). In so specifying, the Legislature has codified 2,100 to 1 as the partition ratio to be used in converting breath test results into blood-alcohol levels.  People v. McNeal, 46 Cal. 4th 1183.