Would you please define "session" as you are using it for the purposes of this thread? Who sets up a session, how and why do the people assemble, what does the management of the hosting venue get out of it, etc.? I skimmed (only quick skimming) through some of the previous threads and it seems as though the crack down is on music for pay.

If it isn't a formal entertainment how can anyone legislate against a group of friends getting together to share a song over a friendly glass of beer?

I think this United Statesian just doesn't understand what it is you do that they are against.