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So if you produce napster 2.0 to be the best music piracy tool, and you test it for piracy, and you promote it for piracy... you're going to have trouble.
If you produce napster 2.0 as a general purpose file sharing system, let's call it a torrent client, and you can claim no ill intent... you may have trouble but it's a lot more defensible in court.
I would find it a big stretch to say Github's intent here is to illegally distribute copyrighted code. No judgment on whether the class action has any merit, just saying I would be very surprised if discovery turns up lots of emails where Github execs are saying "this is great, it'll let people steal code."