So... if i build and sell a "breathalyzer" to your local pd that simply randomly selects a number between .08 and .16, you'd be ok with that? Pretty much every other element of the system is biased toward conviction. Police have quotas. Prosecutors need convictions. Private prisons get more money for more convicts. It would be easy to dodge questions for a long, long time. Why would police administer the test to a sober person? In this one weird example a sober person registered as drunk. oh well, its still good for 99.9% of other cases.

The right to confront your accuser is there for a reason. More and more, software is the accuser. We all, at HN, struggle to make our code correct. Step back, think a second, how do you QA a breathalyzer? How do you deal with variations in sensor packages? Yes, they probably do more good than harm, but are they "accurate"? how do you know that?