Some of you asked for more specific advice. Please note, that I can only speak about California (where I practice)
DUIs:
There are two vehicle codes you can be charged with: VC 23152(a) and VC 23152(b)
Following a DUI arrest, prosecutors will tend to hedge their bets and allege both counts.
The first: VC 23152(a) is typically tough for a DA to prove. The ultimate issue in a DUI case is: was a person 'impaired' to drive at the time they drove a vehicle. It's not illegal to drive with alcohol in your system - it's only illegal to drive if you are 'under the influence', which means: impaired. To prove impairment, a prosecutor typically must show:
i) Poor driving (i.e. weaving, swerving etc.) and
ii) Poor performance on the field sobriety tests (FSTs)
Both are needed. This is why marijuana DUIs (or prescription medication DUIs) are hard to prove.
Why? if you reviewed a standard DUI arrest report, the cop will mention all the stuff a defendant did wrong during the sobriety tests, but often they won't say what the person did right. There are 18 possible 'clues' of impairment on the 3 standardized tests. A cop can say you swayed, missed placing your heel to toe as instructed, put your foot down on the balance test, or pivoted on the wrong foot. Looks bad right? wrong...you just passed 15 of out 18 possible impairment 'clues'. But your arrest report won't be written that way.
'Swaying' from side to side is only a 'clue' if you sway more than 1.5 inches (to my knowledge)
'HGN' (horizontal nystagmus test - the tracking of your eyes) can be affected at .04 BAC or more, meaning, just because you 'fail' such a test doesn't mean you were even close to being impaired.
There are a ton of technicalities to consider.
FSTs (which you don't have to submit to) are tough for a sober person to pull off flawlessly, especially if you have physical injuries. I had a cop demonstrate his own tests on my last DUI trial and he failed them in front of the entire jury (made the case easy to win)
Anyway, that's the (a) code.
The (b) code is harder on defense: In California, if your BAC is over .08, you are presumed to be impaired to drive. I personally don't believe that every single person .08 or above is actually 'impaired' (it varies) but that's what the legislature decided is the legal threshold, so it's the law. Many states are trying to change it to .05...
So, if you are above a .08, you generally can only beat the case via a suppression motion. Suppression motions tend to focus on: cop didn't have a reasonable suspicion to pull you over in the first place, didn't personally observe you driving, prolonged detention, rising BAC levels, illegal arrest etc.
fyi: thanks for the props - wasn't expecting that. Morale boast for me. I'll try and give more advice in the future.