I was on a jury on a DUI case. The defense tried to raise doubts about the veracity of the conclusions the three big pieces of evidence, the field sobriety test, the breathalyzer, and the blood tests. As far as we could tell all procedures relating to the tests were followed, the tests were backed by sound science, and the results (which all agreed with each other) were thus very likely to valid. We convicted.
The guy wasn't crazy drunk or anything, so it felt a little bad convicting someone only slightly over the limit. That being said, I had no reasonable doubt that the evidence showed he was over the limit at the time of being pulled over.
I think the guy got a fair shake and it did give me a more positive perspective on the criminal justice system having been a part of the process. I hope if I am ever on the line a jury discusses and the evidence as a group the way that we did.