The People, Plaintiff and Respondent v. Terry Vangelder, Defendant and Appellant

Summary

The California Supreme Court held that expert testimony challenging the fundamental reliability of properly functioning, calibrated, and approved breath-testing machines was inadmissible in a prosecution for driving with a prohibited breath-alcohol concentration. The court reasoned that the statute defines the offense alternatively by the alcohol concentration in breath, incorporates a legislatively selected measurement framework, and permits challenges only to the particular machine's malfunction, calibration, or operation. The court reversed the Court of Appeal and affirmed the defendant's per se conviction.