An often overlooked, but great nonetheless, defense to a drinking and driving charge is that the Datamaster DMT has accuracy issues when it comes to how much breath somebody blows into the machine. Published academic studies have scientifically shown that the longer the suspect blows on the Datamaster machine, the higher the blood alcohol score is going to register. According to the article by Dr. Dennis Simpson, this increase has been shown to be in upwards of 25%.
Even though this is a known issue with the Datamaster alcohol breath test, the prosecutor is not required to present any expert testimony to the jury regarding this, and instead are allowed to simply make it seem like the breath test is infallible. Of course the reality is that it is not and this issue must be hammered to the jury.