I chased these for an hour and this is the best dissertation I found.
Jumping in here ---
Is the issue patent or copyright?
Alan Cox wrote:
That's a valid point, but in the US anyone can sue anyone else over
just about anything and it's not over till the appeals are used up.
How can you be sure that someone won't claim ownership of some
obscure parts of Linux and sue over that - again?
You can't, but you can at least try not to ship anything which you know
someone else has rights over, which is after all triple damages for
knowingly offending. So I correct myself - if you have $3.6billion feel
free to ship a Fedora with MP3 support.