If the music is in the public domain, no license should be required. A possible rule to adopt: don't play any music at an unlicensed session if you can't document its p.d. status.

It might be fun to hold a bunch of all-p.d. sessions to see if you can lure the copyright cops into making payment demands that they have no right to make. But it might be risky, too. I don't know if I would undertake such a course of action myself, but it's an interesting thought.

Of course, the duration of copyright is now so crushingly long (life+70 in the UK--for a comment on this sordid state of affairs, click here) that many generations must pass before copyrighted music is finally promoted to its true home in the public domain. If the term of copyright were 40-50 years shorter, authors would still have a reasonable chance of making money from their work, but music would become public domain within a reasonable time. There would be more to play at sessions--though still not the newest music--without depriving authors.

Here and here are two law-journal articles dealing with musical copyright. They don't deal directly with questions of performance licensing, and they are written from a U.S. perspective. Still, they might be of interest. The first deals with possible courses of action against those who demand payment for copyrights they don't own, or that don't exist. Some of these legal theories might map into U.K. law. The second deals with the publishing industry's tendency to claim copyright for trivial "arrangements" that may not be copyrightable under U.S. law (and maybe not under U.K. law either).

T.