Any Tacoma DUI attorney will tell you that the Preliminary Breath Test cops “offer” in the field isn’t even allowed in trial for proof of DUI. It gets even better with the Datamaster machine, which went out of production in the late 1980s. Over the years, there have been numerous problems with Datamasters and the people who certify them. One thing even the cops have to agree with is that there is a margin of error in every test. That means that the number the machine spits out about your blood alcohol concentration (BAC) is really only an estimate.
Cops and State experts also have to agree that the machines can give bogus numbers indicating a driver is drunk even if he isn’t. That’s why it’s important to have an experienced DUI lawyer defend you.
These false results are frequently caused by residual alcohol in the mouth of the person being tested. Even if the driver’s BAC is under the legal limit, residual alcohol can cause an exaggerated BAC reading. Residual alcohol can be caused by everything from belching to using mouth wash.
For this reason, the State of Washington requires that officers remove all foreign objects from the driver’s mouth and observe him/her for at least 15 minutes before administering the BAC test. Removing foreign objects (food, dip, studs, gum) prevents alcohol from “hiding” in these items and causing a false high reading. The 15 minute observation period allows the residual alcohol to evaporate off. Of course, officers do not always follow these requirements and this can lead to an inaccurate result.