Imagine you get pulled over. You're sure you've haven't had much to drink, maybe drank just before the stop, and don't feel impaired. You go through the field sobriety exercises on video, you know...follow the pen with your eyes, walk the line, one leg stand, finger-to-nose, alphabet with your head back. The officer feels there's enough proof of impairment to support probable cause for DUI and has you do one more exercise: hands behind your back please and you're cuffed and arrested.
Amazed, you continue to cooperate and provide two breath tests as requested. You blow .08 or more an hour or two after the stop. Well, that's not at the time of driving you think. Too bad. You hire a lawyer, review the video, you look great. Guess what? You still can be prosecuted for DUI, not for impairment but for being over the legal limit if the state files such an alternative DUI charge. Then you CAN'T show the jury the video or tell them you felt fine because it doesn't matter. Its not "relevant".
The state doesn't even have to relate the breath test results back to the time of driving, a numbers crunch extrapolating (estimating) a possible blood alcohol level based on scientifically derived average times to absorb and eliminate alcohol. Cases say up to four hours is O.K between the stop and the breath tests.
Only attacks on the test results by the defense extrapolating (if your expensive expert can make the numbers work), or defects in how the breath tests were conducted or how the machine was inspected and maintained matter. You may employ another even more expensive expert to tear apart how these machines work in general. While that's something, and more than most people can afford, it still leaves you with limited evidence and argument to rebut the readings. Rather than do the right thing and reduce the DUI, watch out that the state doesn't just block the full evidence of the case from the jury by changing the charge to a DUI for simply being over the limit, not impaired.
