In California, the regulations require that breath machines be checked for accuracy at least every ten days or following the testing of 150 subjects, whichever comes sooner. Many law enforcement agencies post the results of these accuracy checks on their website. Orange County Crime Lab does this, as does the Long Beach City Prosecutors Office. In any event, it is a routine step for DUI lawyers in California to obtain a copy of the accuracy checks and maintenance history of breath machines used in DUI cases. If a machine has not been checked for accuracy frequently enough, a motion may be made to exclude the results of the test in evidence. However, most judges view a violation of the rules relating to calibration as relevant to the weight to be given to a test result as opposed to the question of admissability.
Most toxicologists would testify that breath alcohol testing is only accurate of performed on a breath machine that has been properly and frequently checked for accuracy.