I wondered the same thing: if say the Linux kernel was to be re-licensed, how long would it take to get a hold of all the developers that ever contributed something to it? I'm sure some of them have by now passed away, so they'd have to get a hold of their next of kin?
Also, how does duplicating someone's patches work? If I contributed some really basic piece of code, say a very specific hash map implementation where there aren't really two useful ways of doing it, does another developer get to copy/paste bits of it into their code? What if they name the variables the same and structure the code similarly? What exactly distinguishes the original code and the new replacement if they look similar? The fact that someone else typed it in?
I wondered the same thing: if say the Linux kernel was to be re-licensed, how long would it take to get a hold of all the developers that ever contributed something to it? I'm sure some of them have by now passed away, so they'd have to get a hold of their next of kin?
This came up back when the GPLv3 was first being discussed. At the time, as best as I can recall, the consensus was that it would be effectively impossible. I'm pretty sure that it is, indeed, the case that some of the copyright holders have passed away, and I believe there are some that nobody knows how to contact, etc.
All this is, IIRC, a separate issue aside from Linus not wanting to re-license anyway.
If anyone is really especially interested in this particular point, dig around in the /. archives or maybe Groklaw from that era. That and the lkml, of course. There was a decent amount of discussion and gnashing of teeth over this whole issue back then.
IANAL, but as far as I understand it, the theory is that you commit copyright infringement if you copy, that is, you don't come up with the code by yourself (whether you type it or use a copying tool is irrelevant).
How the courts go about deciding whether you actually copied is tricky; it involves actual evidence (emails, testimonial, etc) and common sense, often in the form of expert opinions (you probably didn't just happen to write a 30 kLOC library that implements everything the same way, with just different variable names).
Now, there is a threshold of originality, that is, if there's only obvious way to write something, it shouldn't be infringing. But considering that rangeCheck() was considered to be infringing (see Oracle v. Google), I'm not sure we can depend on that. Then again, the guy did testify he actually copied it.
There's actually some ambiguity over what it would take to relicense Linux. This came up at the time of GPLv3. Torvalds didn't want to relicense it so the question was moot but there was some discussion.
Also, how does duplicating someone's patches work? If I contributed some really basic piece of code, say a very specific hash map implementation where there aren't really two useful ways of doing it, does another developer get to copy/paste bits of it into their code? What if they name the variables the same and structure the code similarly? What exactly distinguishes the original code and the new replacement if they look similar? The fact that someone else typed it in?