[yongjik]

Hence the clarification "willing party". A company "pirates" a GPL'd code, creates its own derivative version, slaps a sticker saying "This is proprietary code, if you want to see the source then go buy from somewhere else." Someone is willing to buy the product, they are both happy. Just like two internet users sharing copyrighted files.

[Andrew_nenakhov]

People can be coerced (fooled, cheated, etc) into believing that they are 'willingly' abandon their rights. This hypothetical example isn't similar to the case we're discussing here in this thread.