Why Lawsuits?: GPL/OSS License Enforcement
People often make the argument that lawyers file suits to get things done because they can bill it and get money from doing it that way. There is, of course, TONS of confirmation bias with so many lawsuits to accomplish so many different ends. GPL enforcement, I think, is a possible counter-example. The foundations litigating these suits often have no particular financial incentive to go to court. The purpose of the foundation, besides survival, is to get the companies to comply with the suits. Yet it often takes a court filing or two before the other company settles out of court (the GPL is almost completely untested in the court of law). It would be good to see the propensity to file where these foundations (and others in similar circumstances) versus purely commercial, profit-driven entities.
See:
BusyBox developers reach settlement with Xterasys
or just this Google search.

