San Diego DUI lawyer Rick Mueller reports on his California DUI Law Center blog about a Kentucky case involving a defendant’s request to inspect the source code for a DUI Intoxilyzer 5000.  The defendant argued that the State should not be allowed to introduce evidence from the Intoxilyzer if the defense was not allowed to examine how the Breathalyzer worked.

This defendant’s argument is known as a "black box" argument – in other words, a defendant should not be convicted based on the readings from a black box that has unknown internal processes.

The trial judge denied the defendant’s motion, as did the circuit court of appeals.  However, the second level appeals court – the Kentucky State Court of Appeals – reversed the prior decisions and granted the defendant’s motion.  The apellate court held that the defendant could examine the Breathalyzer source code as long as reasonable confidentiality procedures were followed.  Presumably CMI, the company that makes the Intoxilyzer 5000, does not want its source code distributed on the Internet.

I wonder, however, how long the Intoxilyzer source code could remain confidential if lawyers throughout the country continue to convince trial judges and appellate courts to allow for review of the source code.   I also wonder what an analysis of the source code will reveal.

In the past I have seen arguments that breath machine results are faulty because the machines are calibrated based on a 180 pound male.  It will be interesting to see what other arguments can be made.