https://lwn.net/Articles/61292/ provides a great explanation

> There is no provision in the Copyright Act to require distribution of infringing work on altered terms. What copyright plaintiffs are entitled to, under the Act, are damages, injunctions to prevent infringing distribution, and--where appropriate--attorneys' fees. A defendant found to have wrongfully included GPL'd code in its own proprietary work can be mulcted in damages for the distribution that has already occurred, and prevented from distributing its product further. That's a sufficient disincentive to make wrongful use of GPL'd program code. And it is all that the Copyright Act permits.

I thought the latest lawsuit from Software Freedom Conservancy was interesting, they are suing as a third-party beneficiary of the GPL (not as a copyright holder, although they probably could do that too in this case) and seeking specific performance of the GPL violator (Vizio) and of course legal costs, but no damages. The specific performance they want is of course GPL compliance. As part of the case, they are basically saying that the GPL is a contract and the contract says that third-parties can get benefits and so they want those benefits. Frankly this is a brilliant case and if they win the precedent will allow anyone to sue over GPL violation. If any trolls try it, all they get is GPL compliance, so they have no incentive to try it.

https://sfconservancy.org/copyleft-compliance/vizio.html

> If any trolls try it, all they get is GPL compliance, so they have no incentive to try it.

Not necessarily. The Conservancy chose not to ask for monetary damages, but that doesn't mean their legal theory inherently precludes asking for them; a troll could still do so. Though (IANAL) it seems like it might be hard as a TV buyer to prove that you were damaged in any significant monetary amount.

What would be the basis for those damages? The GPL itself couldn't provide any but I guess if the troll itself got sued by someone else for GPL violations, they could pass on the legal costs from that suit. Maybe the emotional pain of discovering a GPL violation is worth some damages :)

One bases for damage is that if that project would have complied with GPL you would have saved a lot of money by being able to use that instead of rolling your own, in which case the damage would be development time (potentially very specific) + damage due to time delays (vague).

Depending on the situation a 3rd party beneficiary might have a easier time to lay out the damages and the amount of damages then the first party.

Through not sure how far that would work.

But I mean it is a contract, you are a 3rd party beneficiary and the contract is breached. So it might work.

Anyway that still isn't useful for trolls because they don't lose out on anything as they tend to not produce anything.

New word to me day!

Mulct: extract money via tax or fine.

Oh, I thought it was a variant of "mulch". As in, since these laws were basically written for books and other paper products, have the entire print run shredded.

The problem with answering your questions is that it dependents on the country and my knowledge about this topic isn't deep enough give an answer I would find satisfying.

> But if it's violated after notification

It's violated from the get to go, but it might only get terminated after notification (and a potential grace period) which can have all kinds of stage effects, like a different court being responsible or laws with "less bite" then copyright laws being the relevant laws. There was an interesting case where this happened in France not to long ago (but I forgot the name, it also seem to had other complications).