Well, I can remember an episode (don't ask me to be specific) where a defendant was trying to use sexual orientation as part of their defense. The senior ADA, Jack McCoy, argued before the state supreme court against it in a way that set a precedent (again, don't ask me any specifics) disqualifying the defense from using it. Before he left for his hearing, Serena got pissed and told him not to "expect her help in this case"!
That was the first to raise a flag to me. Then there were other subtle moments, which right this moment I can't recall, but they were there.
Anybody else...