[verall]

(American viewpoint about this device being potentially used in America. Courts and policing is different in Canada, and so my feelings here aren't neccesarily how it would work out there)

In many (most?) states you can refuse the blood test, until they get a warrant, even though you cannot refuse the Breathalyzer. I believe this will be used as a tool to make arrests and generate probable cause which will then immediately be used to obtain a warrant and blood test, which will hold up in court much better than the Breathalyzer alone or nothing at all.

I'm sorry, but even if this product works perfect technically I see it harming more people than it helps. Throw in chance of false positives and likely hood it is used by biased individuals in a biased way (only some individuals are told to blow multiple times, etc) and I really believe this product deployed in America would have a negative impact on most people.