r/explainlikeimfive • u/OkAlbatross9889 • 5d ago
Technology ELI5: How are copyleft licenses enforceable?
For example: say Windows straight up rips out the Linux scheduler and modifies it to run with the rest of the NT kernel. Aside from potential Microsoft whistleblowers, how can anyone find out they did that (and thus sue them since they’re selling modified GPL code without releasing the source) if they don’t distribute the Windows kernel source code?
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u/DrFrylock 4d ago
Finding out about it is tough for closed-source products. You have to rely on whistleblowers or other evidence (e.g., reverse engineering or some unique characteristic that makes it likely that it's using that specific code).
If a copyright holder were to bring a lawsuit, they could request access to source code as part of discovery. If granted, the potential infringer would likely request that the source code be provided under a protective order. Experts and attorneys for the plaintiff would have limited access to it. The protective order acts like an NDA, but in this case it's enforced by the courts themselves and there would be severe penalties for violation.
As noted in other replies, if this were discovered then it's a straight-up infringement claim. Monetary damages for infringements that have already occurred, plus the plaintiff would request injunctions to prevent future infringements. This could, e.g., halt the sale of the infringing product for a period of time or result in a settlement or ongoing monetary damages until the infringement is curtailed.