When a person is given a breathalyzer test, a sample of breath is retained in a reference ampoule. If the breathalyzer test is administered accurately and if the ampoule is retained by law enforcement officials in a proper way, physical evidence exists of the defendant's intoxication or lack of it. If the ampoule can be tested independently, it can provide the defendant with important evidence of whether his due process rights were protected when the test was first administered by law enforcement officials. Criminal discovery procedures have been applied to the breathalyzer test and reference ampoules. To compel discovery, defendants must make a request for the ampoule, must demonstrate that the ampoule is in the prosecutor's possession or control, and must show that discovery of the ampoule is favorable to their particular case, as well as that discovery of the ampoule is material to their guilt or punishment. Few courts have found the reference ampoules to be discoverable. In the future, tougher DWI laws may lead courts to grant discovery of the ampoules in order to protect defendants' rights to due process. 184 footnotes.