Dismissed DUI Reinstated After Prosecutor Appeals Exclusion of Retrograde Extrapolation Evidence

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Benjamin F. Warlick got into a traffic accident and California Highway Patrol Officer Chris Jensen came to investigate.

Mr. Warlick told the CHP officer he had been drinking alcohol earlier in the evening. The reading from a preliminary alcohol screening (PAS) test showed that Warlick had a blood-alcohol level of 0.07 percent at approximately 12:17 a.m.

The prosecution charged Mr. Warlick with violating section 23152(b), which makes it “unlawful for any person who has 0.08 percent or more, by weight, of alcohol in his or her blood to drive a vehicle.”

Warlick’s DUI defense attorney made a motion to exclude any expert testimony based on retrograde extrapolation analysis.

At the pretrial hearing, Marisa Ochoa, a criminalist from the San Diego County Sheriff’s Department testified for the prosecution. Ms. Ochoa testified that based on the PAS test result, Mr. Warlick’s statements about his drinking, and studies regarding normal alcohol elimination rates, Ms. Ochoa’s opinion was that Mr. Warlick had a BAC of at least 0.08 percent at the time of driving.

Judge Edward P. Allard III ruled Ms. Ochoa’s proposed testimony inadmissible based on Baker v. Gourley (2002) 98 Cal.App.4th 1263. The court said according to Baker that a violation of section 23152(b) cannot be proved without a chemical test showing a blood-alcohol level of 0.08 percent or greater.

The prosecutor told the court he could not prove a violation of section 23152(b) without retrograde extrapolation evidence. (Retrograde extrapolation is the calculation back in time of the BAC.  It is an estimate of the level at the time of driving based on a test result from some later time.)

The trial court dismissed the charge. The prosecution appealed.

The Appellate Division of the Superior Court in San Diego disagreed with the trial court. It said that Baker v. Gourley did “not stand for nearly so sweeping a proposition.” It further said, “The Baker decision is limited by its terms to the “so-called ‘Admin Per Se’ laws where the … [DMV] suspends a driver’s license…”

In distinguishing Baker, the Appellate Division also noted, “the factual context of that case is of crucial importance in understanding the scope of the holding. Baker’s statement precluding reliance on circumstantial evidence was based expressly on the lack of a “valid chemical test. Here in contrast, there was a perfectly valid chemical test—that happened to show a blood-alcohol level of only 0.07 percent.”

The characterization of the PAS test as a chemical test is curious.

Vehicle Code Section 13388 says “a preliminary alcohol screening test device is an instrument designed and used to measure the presence of alcohol in a person based on a breath sample.”

Vehicle Code Section 23612(h) says, “A preliminary alcohol screening test that indicates the presence or concentration of alcohol based on a breath sample in order to establish reasonable cause to believe the person was driving a vehicle in violation of is a field sobriety test and may be used by an officer as a further investigative tool.”

Vehicle Code Section 23612 (a) (1) says a chemical test comes after arrest: “A person who drives … is deemed to have given his or her consent to chemical testing of his or her blood or breath for the purpose of determining the alcoholic content of his or her blood, if lawfully arrested for an offense … in violation of Section … 23152 …”

Whether or not the court took the above vehicle code statutes in mind, the court reversed the trial court’s decision.

It reinstated the section 23152(b) charge and denied the request to exclude the retrograde extrapolation testimony.

The citation for this opinion is People v. Warlick (2006) 162 Cal. App. 4th Supp. 1.

If you’ve been arrested for a DUI, contact The Law Office of Richard Wagner at (714) 721-4423.

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