December 5, 2013 By Matthew Wallin

In People v. Vangelder, the California Supreme Court ruled a trial judge overseeing a DUI case properly excluded expert testimony that challenged the overall reliability of breath-alcohol testing machines. In a unanimous opinion, the court held that a defendant charged with driving with a blood-alcohol level of 0.08 percent or more, in violation of California Vehicle Code section 23152(b), can argue that a particular breathalyzer machine used to convict him was faulty. However, an expert witness cannot challenge the overall reliability of such devices since the Legislature determined as a matter of policy that they are reliable for purposes of evidential use in a criminal prosecution, the court said.

People v. Vangelder

cannot challenge breathalyzer
In a recent decision, the California Supreme Court ruled an expert witness called upon by the defense cannot challenge breathalyzer test validity.

The case involved Terry Vangelder, who was pulled over by the California Highway Patrol for speeding and consented to take two tests using an Intoximeter Alco-Sensor IV, a handheld breathalyzer device. The device indicated that Vangelder had a blood alcohol level of 0.095% on the first test, and 0.086% on a second test administered two minutes later. California Highway Patrol arrested Vangelder and subjected him to additional breathalyzer tests at the county jail using an Intoximeter EC/IR device which indicated an alcohol level of 0.08%.

Vangelder was charged with misdemeanor counts of driving under the influence of alcohol in violation of Vehicle Code §23152(a) and driving with a blood-alcohol concentration of 0.08% or more, in violation of §23152(b). During trial, the defense called a professor of medicine as an expert witness.

The defense expert testified that breathalyzer tests were “inherently inaccurate” because they worked on a false assumption that the alcohol concentration in one’s breath is directly related to the amount in one’s blood. The expert said that such breath tests were only an “indirect” means of determining blood alcohol levels and that even if the breathalyzer devices operated properly as designed, they could be impacted by a variety of psychological factors and would not produce scientifically reliable results.

The jury heard portions of the expert’s testimony, while other portions were offered in hearings outside of the jury’s presence to determine admissibility.

The trial court ruled that the expert’s testimony concerning the overall reliability of breathalyzers was speculative and inadmissible, but that he could still testify that the particular machines used in Vangelder’s case were not operating properly and that their results could be contaminated by “mouth alcohol,” which dissolves into mouth tissues and does not reach the bloodstream.

The Court Rules Expert Witnesses Cannot Challenge Breathalyzer Test Validity

The jury could not reach a verdict on the generic charge of driving under the influence, but found Vangelder guilty under §23152(b) of driving with 0.08 percent or more alcohol in his blood. The Court of Appeal reversed the conviction, holding that the expert testimony was improperly barred and should have been allowed. However, the Supreme Court disagreed, holding that the expert’s statements were properly excluded because they were incompatible with legislative determinations that could not be challenged.

Chief Justice Cantil-Sakauye wrote that the court’s previous decision in People v. Bransford (1994) 8 Cal.4th 885 concluded that amendments to §23152(b) in 1990 showed a legislative intent to criminalize driving with a specified alcohol level determined from either a suspect’s blood or breath. The Bransford ruling also concluded that the amended law rendered conversion methodologies that determined blood-alcohol levels from breath samples to be irrelevant because the revised statute “defined the offense without regard to such ratios.”

The California Supreme Court decision in People v. Vangelder does not serve to prohibit the defense from presenting evidence on whether the test measurements themselves were inaccurate or whether the breath tests were improperly administered in violation of Title 17 of the California Code of Regulations. However, the decision does serve to prohibit a defense expert from challenging the validity of breath testing in general.

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