In a classic illustration of how the legal system works in DUI cases, the Montana Supreme Court just ruled that results of handheld breath devices used by officers in the field are admissible in evidence — after years of ruling that they were unreliable and inadmissible:

In a 5-2 vote the Montana Supreme Court decided Tuesday to allow a preliminary breath test for alcohol consumption to be used as evidence.

The case of State of Montana versus David Damon involved a DUI stop in 2002 in which a preliminary breath test (PBT) was conducted on Damon…The case was appealed by Damon who argued the District Court "abused its discretion" in concluding the PBT was reliable…

This was not the first time the PBT has come up before the Montana Supreme Court. Throughout the written opinion three cases are cited. In all three cases the court found against the PBT, specifically that the State did not provide enough evidence to prove the "statistical reliability" of the PBT….

Montana Supreme Court Justice Patricia O. Cotter wrote an 11 page dissent.
Citing previous court rulings, Cotter expressed her view.

"I am at a loss to understand why we feel so constrained to buck the well-reasoned national trend and admit these results as substantive evidence of guilt. Nothing has changed … to deem these machines magically more trustworthy than they were just a few months ago, or to justify this about-face in our jurisprudence," Cotter wrote in conclusion of her remarks.

If rules get in the way of convictions, change them….