Breathalyzer Source Code as an Issue in DUI Defense

By Dean I Weitzman, Esq. on June 25th, 2009

For years, DUI defense attorneys have questioned the reliability of breath test results used as evidence of alcohol intoxication in DUI cases. Criminal defense attorneys across the nation have suggested that the source code used to program alcohol breath test machines have errors that make the machines render unreliable results in certain circumstances.

Reliability of the results is important because in a criminal prosecution, defendants have a right to cross-examine witnesses against them. But for evidence provided from a machine, however, the defendant cannot cross examine the machine, although it provides evidence against the defendant.

The New Jersey Supreme Court has considered the reliability of these machines and analyzed whether the source code—the programming code used to run the breath test machines—accurately programs the machines to provide reliable results. Ultimately, the New Jersey Supreme Court considered the breath test machine used in that state, the Alcotest, manufactured by Draeger, Inc., to be reliable. Courts in Minnesota and Arizona have also considered the source code issue as it relates to the breath test machines used in those states—both use versions of the Intoxilyzer, manufactured by CMI.

In Pennsylvania, law enforcement officers also use a version of the Intoxilyzer in breath tests of drivers they suspect of drunken driving. But Pennsylvania courts have apparently not considered the source code issue yet. Cases in which a court considers the source code for a breath test machine can have far-reaching effects. A finding that the machine renders unreliable results of intoxication because of mistakes in the source code can affect any driver that is currently facing charges of drunken driving based on evidence of a breath test taken on the machine. Future challenges to drunken driving charges in Pennsylvania based on source code could change the way that DUI offenses are investigated and prosecuted in Pennsylvania.