Florida is a time of driving state. By that, I mean that the crime that the state has to prove you guilty of is that you were driving a car while you had an illegal alcohol limit. That's when you were initially stopped. You don't take the breath test generally for about an hour to an hour and a half later. In the misdemeanor DUI cases, the state retrograde extrapolates that number back to the time of driving, so there are built-in defenses just because you were over the limit.
Secondly, you can impact the way the machine is actually used. The machine that we use in Florida now, the Intoxilyzer 8000, is not specific for ethyl alcohol. It may have interfering substances that may read as alcohol which is not actually alcohol. Secondly, the way the machine is used. The machine is calculated based upon something called a partition ratio of 2,100:1. In other words, the machine measures what it thinks is alcohol and then multiples that number times 2,100. Now, if your partition ratio is less than that, then they have overestimated your alcohol level.
The bottom line is that they never know what your alcohol level is when you were driving the car or the machine, whatever it says that it is.