She was a co-professor for my criminal pre-trial practice class, which was the hardest class I've ever had, in law school or for my engineering degree. It wasn't conceptually hard, it just required so much work. Every week we were given facts for two different cases and had to write motions for both the prosecution and defense.
At the time she was a prosecutor, and the other professor was a defense attorney. It was only a 2 credit class, but I spent hours and hours researching case law for those motions. As a result, though, criminal law is the only other field I would have felt comfortable going into when I graduated.