"In Illinois, recording law enforcement officers without their consent is considered a serious crime — or at least the authorities choose to interpret an old eavesdropping statute that way. According to WBBH, 12 other states have a similar interpretation of the law, including Florida, Massachusetts, and Maryland."

Illinois Man Faces 75 Years in Jail for Filming Police

I'm still digging around to see if I can find the statute this article is talking about.