The Breadth of Admissibility: A Survey of BAC Margin of Error Evidence in DUI Cases

DUI cases make up the bread and butter of most criminal dockets.  One of the primary evidentiary tools for these cases is some sort of BAC testing instrument.  Like any piece of scientific equipment though there is a margin of error inherent in the testing procedure and equipment.  This margin of error has been the source of significant litigation across the United States, where defense attorneys have attempted to introduce the testing margin of error as something for the jury to consider when analyzing the BAC test.  There is a majority and minority view held by the sister-states concerning the admissibility of blood alcohol test margin of error.  The majority view is that margin of error is admissible and can be considered for the weight of the evidence, the credibility of the evidence, or for attacking a statutory presumption of intoxication.  The minority view is that the margin of error is inadmissible because the statute already takes it into account or only goes to the validity of the test and not to its evidentiary value.  It should be noted though that the following is not a complete survey of all fifty states, because some states do not have as extensive case law on point or dip into administrative or civil license forfeiture decisions for basing their analysis on BAC testing margin of error.