Defendant's conviction for driving while having a proscribed alcohol concentration in blood or breath is affirmed, where the trial court properly excluded expert witness testimony challenging the reliability of breath-alcohol testing machines. Although defendant can argue, and present evidence, that the particular machines used in this case malfunctioned, or that they were improperly calibrated or employed, the fundamental reliability of federally approved, properly calibrated and employed breath-testing machines used in the application and enforcement of the per se statute is a matter that has been determined as policy by the Legislature, and a defendant's expert witness may not invite a jury to nullify that determination in the manner at issue here.