Is there any prior case where an court demanded that a party comply with a copyright license? "stop using it or comply with the license" seems to be the obvious step for any infringer.
In the case of the GPL, the "or comply with the license" doesn't even apply. As soon as you violate the license, the license is terminated. This is to stop people from violating the license and then saying, "Ok, Ok, I'll comply" when they are threatened with a lawsuit. In practice, copyright holders usually forgive the other party and offer then a new license, though. So, again from my layman's point of view, I don't think this is an issue since the court can't force the other party to disclose their source code. It can only grant an injunction on distribution.
In every case, the use of the license (and subsequent release of the source code) is a choice. Of course, without choosing to follow the license, you can't distribute the software. As far as I understand, this is by design and the reason why the GPL is so robust.
I also think this is a negotiated license because the GPL specifically says that you don't have to accept it. It is a written offer for a license. Sometimes, if you contact the copyright holder you can get a different license. Usually now. Just because the offer is made to everybody, doesn't mean it is not a negotiation (I don't think... but that's probably where knowledge of the law would come in handy ;-) ).
In every case, the use of the license (and subsequent release of the source code) is a choice. Of course, without choosing to follow the license, you can't distribute the software. As far as I understand, this is by design and the reason why the GPL is so robust.
I also think this is a negotiated license because the GPL specifically says that you don't have to accept it. It is a written offer for a license. Sometimes, if you contact the copyright holder you can get a different license. Usually now. Just because the offer is made to everybody, doesn't mean it is not a negotiation (I don't think... but that's probably where knowledge of the law would come in handy ;-) ).