That sucks man. My GF got a DUI a couple weeks ago, but she hasn't went to court yet so I can't really offer any suggestions. I wish everyone who hasn't tried marijuana would quit acting like it's so f-ing bad. It does not make you more dangerous than anyone sober. If anything it makes you drive safer. Don't believe me, then TRY it! Alcohol is a different story. Did you admit to smoking? THC can be in your blood for 30 days (as I'm sure you know). So unless he smelled it, or you admitted it there is no way they can prove you were under the influence.