Not a lawyer. A copyright license is a written agreement not dissimilar from a contract. However, validating the contract usually doesn't come up, because the

Not a lawyer. A copyright license is a written agreement not dissimilar from a contract. However, validating the contract usually doesn't come up, because the violator needs the agreement to be valid to avoid copyright infringement. > Because the GPL does not require any promises in return from licensees, it does not need contract enforcement in order to work. A GPL licensor doesn't say in the event of trouble "But, judge, the licensee promised me he wouldn't do what he's doing now." The licensor plaintiff says 'Judge, the defendant is redistributing my copyrighted work without permission.' The defendant can then either agree that he has no permission, in which case he loses, or assert that his permission is the GPL, in which case he must show that he is obeying its terms. A defendant cannot simultaneously assert that the GPL is valid permission for his distribution and also assert that it is not a valid copyright license, which is why defendants do not 'challenge' the GPL. https://lwn.net/Articles/61292/ https://lwn.net/Articles/61292/ However, I believe only the copyright holder can sue for copyright infringement, so this case is instead taking that oft-skipped step of validating the contract so it can further claim SFC is a party of the contract. Infringement cases also have specific rules about damages, which can make it hard to actually get the infringer to do anything when you give the software away for free. IMO the "specific performance" seems likely to be granted if they win the case on contract grounds. There was another recent case where they seemed to rule the GPL could be enforced as a contract, but I'm not familiar: https://www.theregister.com/2017/05/13/gnu_gpl_enforceable_contract/ https://www.theregister.com/2017/05/13/gnu_gpl_enforceable_c...