(1) Did the police perform a legal detention, search or arrest? If not, the Court may bar the prosecution from introducing evidence obtained from an illegal detention, search or arrest. I have seen cases where the Court prevented the prosecution from introducing evidence of drugs and open alcohol containers where the evidence was obtained after an unlawful search.
(2) Did the police properly perform the chemical testing to determine your intoxication? When a police officer uses chemical testing equipment, he is required to follow certain requirements set out by the State of California AND the equipment manufacturer to ensure a fair and accurate testing. If a police officer fails to follow the proper procedures the Court may prevent the prosecution from introducing evidence of the testing results. This is so even if the results may have been accurate.
(3) Were the alcohol screening and chemical testing devices properly maintained and calibrated? Even though the results of the testing may have been accurate, if your attorney can prove that the equipment used was not properly maintained or calibrated the results of the test may be excluded from use by the prosecuting attorney. This line of attack is slightly different from (2) above as it deals with the equipment prior to your testing while (2) deals with how your testing was performed.
(4) Can the prosecution prove that you were the one driving the vehicle?
(5) Were you tested within three hours of driving the vehicle?