Most drunk driving charges are typically based on a blood alcohol concentration test. There are a variety of brand names in the field of breathalyzer testing, however, it is important to keep in mind that breathalyzers do not test blood alcohol concentration (BAC). Testing blood alcohol concentration actually requires the analysis of a blood sample. BAC is estimated indirectly through the use of breathalyzer tests.
The different types of breathalyzer machines operate differently and larger machines typically tend to provide better results than smaller, hand-held, breathalyzer machines. In some states, data from hand-held machines may not be presented as reliable evidence in court. In addition, some states only use blood tests to protect the innocent and those wrongfully accused of a drunk driving crime.