What's the meaning of "damages" of copyright infringement under a copyleft license?

Question

As a general rule, civil suits for copyright violation exist to recover damages caused by the violation, and prevent future damage thereof. Under that standard, a rather novel form of copyright seems impossible to defend: copyleft licenses.

Copyleft, the common descriptor for copyright licenses which allow free use provided any derivative works are released under similarly free terms, attempts to force the spread of open content (most typically software) through clever usage of conditional license grants, most notably used in the GNU General Public License. But how could this possibly be enforced in court? Because this sort of license was designed to guard against violation of one's beliefs, rather than financial damage, in the case of a violation, it would seem one could only claim moral damage.

In short, how would one possibly justify a copyleft violation suit in a court of law?

Edit:

For the purpose of this question, I'm referring alternately to either US law or EU law, as I'm curious about both given the clear differences in intellectual property law between the two.

Answer 1

As a general rule, civil suits for copyright violation exist to recover damages caused by the violation, and prevent future damage thereof.

With respect to US law, that's not entirely accurate.

Under US law, damages for copyright infringement are governed by 17 USC 504. If infringement can be proved, the copyright holder has two options:

1. Recover "actual damages" plus any profits that were attributable to the infringement. So suppose Alice licenses her free software under copyleft. Bob uses it in violation of the license to create a product which he sells. Even though Alice was not going to make any money by selling the software herself (so her actual damages are zero), she can still recover whatever profits Bob made from his sales. She doesn't have to prove that she was damaged; all she has to do is show that Bob earned revenue attributable to the infringement (and then it is up to Bob to show how much of that revenue went to expenses instead of profit).

2. Recover statutory damages. The law specifies statutory damages of $750 to $30,000 per work infringed, to be determined by the court; this can be increased to $150,000 if the infringement was willful, or reduced to $200 if the infringer had no reason to know he was doing so. Again, it doesn't matter that Alice didn't suffer any actual damages, and she doesn't have to prove that she did. It also doesn't matter whether Bob profited from his infringement in any way, and again Alice doesn't have to prove that he did.

So Alice certainly has options to make Bob suffer for his infringement even if she didn't suffer any financial damage.

I don't know the situation for EU law, so I'll let someone else address it.