IANAL, but if I understand correctly, to claim copyright infringement, they would have had to register the work with the library of congress, and essentially make it publicly viewable - which I assume they didn't want.
Copyright in this kind of case is usable almost exclusively by GPL style licenses, where the code is already available.
Registering allows you to sue for more money than if you don't register, but any creative work is automatically protected by copyright law (including full rights to control and prevent reproduction/distribution) automatically as of the moment the work is first fixed into a "tangible form of expression".
That's not entirely correct. From the U.S. copyright statute, 17 USC 411: "... no civil action for infringement of the copyright in any United States work shall be instituted until preregistration or registration of the copyright claim has been made in accordance with this title." [1]
(The term "United States work" is defined in 17 USC 101 [2]. There are certain exceptions, unlikely to be relevant.)
So if you find out someone is infringing and want to sue, you begin registration for copyright and file suit shortly after. It doesn't say it had to be registered when the infringement happened.
> So if you find out someone is infringing and want to sue, you begin registration for copyright and file suit shortly after. It doesn't say it had to be registered when the infringement happened.
Technically that's correct -- but there are some possible adverse consequences if you don't register before the infringement begins (or alternatively within a three-month window after first publication). Specifically:
a) you forfeit the option of seeking "statutory damages," and instead you have to prove up your actual economic loss and any additional profits made by the infringer arising from the infringement; and
b) you don't get to seek attorneys' fees from the infringer if you win --- but if the infringer wins, the infringer can still seek attorneys' fees from you.
Registering allows you to sue for more money than if you don't register,
Maximum is $250,000 per infringement if it is registered (and possible jail time for 10 or more infringements). If it is not registered then liabilty is just (simplified version) the retail price of each work infringed.
So, without registering it and without ever pricing it for sale, it could be argued that the damages would be $0.
Copyright in this kind of case is usable almost exclusively by GPL style licenses, where the code is already available.