On what grounds have you challenged the validity of breath tests?

Transcript:

There are so many ways to challenge the validity of breath tests. It is scientific practice that is used because it is convenient not because it is accurate and not because it is particularly effective. Challenges to breath tests can range from the observation period that needs to be conducted prior to a breath test to how the operator actually administers the test itself to how those results are even reported. Whether the machine is as accurate as it claims to be I mean we’ve had experts from the Minnesota Bureau of Criminal Apprehension get on the stand and testify that somebody whose test results said a .09 could have actually been less than a .08 due to inaccuracies with the machine itself. So really, starting even before the test going through any potential error codes or problems with the test straight through to how those result are ultimately reported and interpreted there are many, many ways to challenge a breath test in court.