Breath testing in the DUI context has remained the work horse over the years in providing law enforcement with scientific evidence of impairtment.  Law enforcement has advocated that breath testing remains a relatively reliable form of obtaining the BAC from an individual and furthermore, it remains a relatively inexpensive manner of evidenciary testing.  Naturally there is also much criticism regarding the relability of breath testing. 

There is little debate in the DUI community that breath testing is an inferior method of testing an invidivual’s blood alcohol concentration in comparison to blood.  However, it is equally agreed that breath testing does have some advantages over a blood draw, those primarily being that it is cheaper, faster, gives immediate results, and is less invasive.

The biggest problem with a breath test compared with a blood test is reliability.  Since the 1970s, researchers have warned scientists and those who use breath testing devices of factors that can affect a reliable breath alcohol (BAC) reading.  Mason, M., Dubowski, K., Breath-Alcohol Analysis: Uses, Methods, and Some Forensic Problems.  Review and Opinion.   J Forensic Sci. (January, 1976)  The primary factors that can potentially affect the accuracy of a breath testing machine include physiological factors, machine characteristics, and administrative practices.

In the State of Washington the BAC Datamaster and the BAC Datamaster CDM are the only machines certified for use in DUI cases.  In 2011 the Draeger BAC machine will be added to this list.