In legal proceedings involving driving under the influence (DUI), the testimony of an Alcohol, Drug & DUI Testing Expert Witness can be pivotal in determining the outcome of a case. A notable example is the case of People v. Vangelder, which delved into the admissibility of expert testimony challenging the reliability of breathalyzer tests.
Background of the Case
In People v. Vangelder, the defendant, Terry Vangelder, was stopped by the California Highway Patrol for speeding and subsequently subjected to breathalyzer tests. The initial tests, conducted using a handheld device, indicated blood alcohol concentrations (BAC) of 0.095% and 0.086%. Further tests at the county jail using a different device showed a BAC of 0.08%. Vangelder was charged with misdemeanor counts of driving under the influence of alcohol and driving with a BAC of 0.08% or more, in violation of California Vehicle Code §23152(a) and §23152(b), respectively.
Defense’s Position and Expert Testimony
During the trial, the defense sought to introduce testimony from a medical expert to challenge the overall reliability of breathalyzer devices. The expert contended that such devices are inherently inaccurate due to their indirect measurement of blood alcohol levels through breath analysis. He highlighted various physiological factors that could affect the results, arguing that breath tests are susceptible to errors and may not provide scientifically reliable measurements of a person’s actual BAC.
Court’s Analysis and Ruling
The trial court permitted the expert to testify regarding potential inaccuracies specific to the devices used in Vangelder’s tests, such as issues arising from “mouth alcohol.” However, the court excluded testimony that broadly questioned the general reliability of breathalyzer machines, deeming it speculative and inadmissible. The jury ultimately found Vangelder guilty under §23152(b) for driving with a BAC of 0.08% or more.
On appeal, the California Supreme Court upheld the trial court’s decision, emphasizing that legislative determinations have established the reliability of breathalyzer devices for evidentiary purposes in DUI prosecutions. The court concluded that while defendants can challenge the functioning and accuracy of the specific device used in their case, they cannot present expert testimony to dispute the general reliability of breath testing instruments as a whole.
Implications
The People v. Vangelder case underscores the critical role of Alcohol, Drug & DUI Testing Expert Witnesses in DUI litigation. It highlights the boundaries within which expert testimony can be utilized to challenge evidence, particularly concerning the scientific validity of testing methods. Legal practitioners must navigate these limitations carefully, focusing on specific inaccuracies or malfunctions in testing devices rather than questioning the overall reliability of approved testing methodologies.
Case Citation: People v. Vangelder, 58 Cal.4th 1 (2013).