Rick,
I've tried to reply at length below on the issue of license (in)compatibility.
The below is probably the most I've ever written on the subject, but it's in
some ways a summary of items that discussed regularly among various Free
Software licensing theorist for the past decade, particularly Richard Fontana.
Rick wrote yesterday:
It's a fair, interesting, and relevant question, and I'd really like to
know the answer.
Most things in policy, unlike science, aren't a technical problem where we
can provide a hypothesis and test the results. So, there probably isn't an
answer. I've observed that many lawyers often build their careers on
*pretending* that there are answers to questions like this. Then, they
simply bluster their way through to convince everyone. Since IANAL (and,
BTW, TINLA), I don't tend to think that way. I won't pretend license
compatibility is a testable scientific fact like Einstein's theory of
relativity; it's a policy analysis and conclusion, based on what those doing
the analysis think is correct and likely to be permissible under copyright.
I'd actually be interested in Bradley ... pointing to any caselaw that
supports [his] view.
So, most importantly, I don't think there has been any litigation anywhere in
the world regarding license compatibility. Specifically, Jacobsen
v. Katzer didn't consider it AFAICT. And, (speaking as someone who has
either advised the Plaintiff and/or actually been the 30(b)(6) witness for
Plaintiff in all of the GPL enforcement lawsuits in the USA), I'm not aware
of the license compatibility ever coming up in USA litigation. Also, note
that, no one else in this thread has put any license compatibility caselaw
forward; it just doesn't exist, AFAIK.
However, even if there were caselaw, I don't think looking at the caselaw
record is somehow the only way to consider these questions. My primary point
throughout this thread is that Free Software projects are regularly concerned
about compatibility (and license proliferation too), for good policy and
project health reasons; not because of what some Court said.
I'd suspect everyone to agree that you must meet the redistribution
requirements of all copyright licenses for a given work to have permission
to redistribute. Thus, license compatibility *exists* as a concept because
if you make a new work that combines two existing works under different
licenses, you have to make sure you've complied with the terms of both
licenses. Again, I'd be surprised if anyone disputes that as a necessary
task and requirement.
Where people disagree is about whether or not you actually need copyright
permission at all to create that new work. Some have a theory that it's
virtually impossible to ever need such permission. I'm pretty sure that
can't be right, and there is a lot of caselaw on *this* subject, but the
tests that courts have come up are *highly* dependent on the facts of a
specific set of circumstances for a specific work. (Dan Ravicher's article
the Software Derivative Work: A Circuit Dependent Determination is a
seminal source on that subject about the USA situation. Till Jaeger's talk
at FOSDEM, a recording of which I already linked to in this thread,
covered the European side quite well IMO.)
Of course, derivative works analysis has almost *nothing* to do with
license compatibility. It's just that folks love to fall into derivative
works debates because it's an interesting topic, and because those whose
primary goal is to circumvent copyleft as much as possible (and I've found
that's most people who work as Open Source legal experts) prefer to point
to the derivative works issue as some sort of insurmountable problem that
is therefore the base case of every discussion about Free Software
licensing. And, as you saw, this thread descended into that debate too. I
suspect that's what led Luis Villa to have his oh no, not again reaction.
Meanwhile, license compatibility, as a concept, is a lex mercatoria.
(Fontana and others have talked at length about how much in Free Software
licensing are leges mercatorum; ironically, the derivative work question may
be the only central issue that *isn't* a lex mercatoria.) Specifically, no
court anywhere in the world, to my knowledge, has sat down and lined two Free
Software licenses up next to each other and tried to determine if, upon
creating a whole work based on two works under the two licenses, if the terms
of any license was violated and thus the distributor of that whole work
infringed copyright of one party or the other.
Thus, people argue about what a court might say. Some lawyers bluster and
claim they know the answer when they really don't. (This is why I love Till's
first FOSDEM slide: he admits, as a first principle, the Socratic Epiphany
inherent in this type of work.) In the meantime, though, we have to operate,
share code, and (hopefully) uphold software freedom -- with the tools we have.
That's what led me, back when I started working
