The police must follow specific procedures if they have you submit to a BAC test. They cannot request a BAC test until after you have been arrested. There must be a 20 minute “observation period” before you take the test, wherein the police must make sure you don’t eat anything or regurgitate, thereby interfering with the test results. The testing equipment must be regularly inspected and maintained to ensure accuracy.
If any of these requirements are not met, the results of a BAC test may be subject to a Motion to Suppress.