There is at least one model where, if the officer covers the outlet tube, the reading doubles extremely reliably. I saw this tested in a short documentary some

There is at least one model where, if the officer covers the outlet tube, the reading doubles extremely reliably. I saw this tested in a short documentary some years back. If you're going to get breathalyzed, will you notice if the officer is doing something shady? Could you even know, without knowledge of the various machines? I'm also quite miffed that a cop can give you a DUI even if your reported (by the machine) BAC is under the legal limit, 0.00 included.