there. you may know about the lawsuit by a documentary filmmaker against Warner-Chappell for controlling the right to the Happy Birthday song.
http://boingboing.net/2015/08/07/the-twisted-history-of-the-hap.html
I don't know how this will turn out (and by the way IANAL).
If the Court rules against Warner--Chappell (let's say they find that copyright control ended in 1998), would there be grounds for everybody who paid licensing fees during the intervening time to recover those amounts? (I'm assuming there's no deception or fraud on the part of Warner-Chappell). Would there be grounds to recover damages retroactively?
Is a class action suit a viable mechanism to recover these amounts?
I know this is all wild speculation, but I have always wondered whether there is legal risk in wrongfully keeping something under copyright. Thanks.