The Missouri Supreme Court ruled last week that the word “and” is important. It appears that the regulations governing the calibration of breathalyzers in the state had an inadvertent, but significant, mistake. The regulations that were in place from December of 2012 until January 2014 stated that breathalyzers had to be calibrated at vapor concentrations of 1.10, 0.08 and 0.04 percent.

This regulation had been intended to list the concentrations as “or” not “and,” meaning it only had to be calibrated at a single value, and that is what had been customary. However, agencies are not permitted such sloppy proofreading, and the Supreme Court ruled that any breathalyzer reading from a machine not calibrated to all three values during that period were invalid and not admissible.

This ruling by the court could be dismissed as technical and it is unlikely that it will have a very large effect on DWI cases, with the exception of those cases dating from that period. Of course, even in those cases, the prosecutors may still put the arresting officer on the stand and he or she may testify that there were other factors that suggested that the accused was guilty of a DWI.

Nonetheless, court cases like this are important. The breathalyzer is a black box. Only a few chemists and software experts fully understand the mechanical processes it uses to convert a breath into a number that is supposed to indicate the concentration of alcohol in the blood. Most of us have to trust they really are doing what they claim they are doing.

It is essential that these systems be very closely watched and examined, to ensure that police, prosecutors and the courts do not become lazy and merely rubber stamp the output of these “magic boxes” without independent and rigorous examination.

Source: news-leader.com, “Missouri Supreme Court decision might apply to some pending DWI cases,” Harrison Keegan, January 15, 2016