For ISM, yeah the FCC don't give a shit.

Marriott was jamming for years, until they were forced to stop. Keyword: years.

If someone is making temporary jamming attacks (even on GPS or cell), unless you do it at your house or stationary, you ain't getting caught.

I know 'a friend at the hackerspace' who did a .25w GPS spoof to make the city look like it was in Moscow, Russia. Nobody responded.