@oantolin @fsf A few, most of these things never end up in court since lawyers know what is at stake. The Objective-C addition in GCC was one of those cases. GNU readline and GNU CLISP is another that is sorta famous.
The Copyright Assignment is a tool to minimise damage from those who want to harm free software, it is a small hurdle that has a proven record of working well in defusing sticky situations, plus ... _you_ don't need to enforce the GNU GPL or such, which is the real benefit.