Broc, I'm sure I read the woman who "released" the tapes was his archivist. Her role then is to record conversations (I read somewhere, I don't know how accurate, that she has over 100 hours of conversation with him). He knew he was being recorded, but he didn't know that it would be released, and therefore would be used in the court (but again, this may not be reliable, so have any facts to prove me wrong).
Also, here in the UK, a racist remark on Twitter gets a six-month prison sentence. In my humble opinion, the First Ammendment is a pile of wank, because it allows politically incorrect, bigoted people like Sterling, to get off offences like this relatively scot-free.