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.
That leaves reasonable doubt. Reasonable doubt favors the accused. If your device removes reasonable doubt, it does not benefit the accused.