Driver slams into multiple cars in Roxbury, flips over, gets out and runs away

They have a ludicrous false positive rate, and preliminary breathalyzer test results (the kind administered in the field) aren't even admissible as evidence of OUI in Massachusetts and many other state courts. High results can be used as justification to arrest someone and bring them to the station, at which point more accurate tests are administered, but the devices just don't work well enough to be used as evidence themselves.

It would be great if we had reliable, portable scientific ways to determine if someone is impaired, and if we did, I could see putting them in as safety features on all of our vehicles. But such tests don't exist at this time, so it would be a disaster if we tried to roll them out that widely. Sober people would wind up getting stranded in their cars too often.