When to evaluate dual licenses (was: license categories, was: I'm not supposed to use the ECL v2?)

[Lawrence Rosen]

> This comes back to my original claim: that if you received code under a
> dual license, you have all the powers granted by either license;
> in this case, the power to issue your derivative work under the GPLv2.

To paraphrase Bill Clinton, that depends on what the meaning of "or" is.

If I accept software under a "License A or later" option, and License A is
reciprocal/copyleft, then one interpretation is that the "License A or
later" choice remains with the work and its derivative works forever. The
other interpretation is that the "or later" choice is intended to be
irrevocable as to a downstream distribution and its derivative successors. 

So too, in a more traditional dual-licensing "License A or License B"
scenario, where both licenses are open source, we have two possible answers.
Both license choices would remain available for all future derivative works
*or* a choice, once made, is intended to be irrevocable as to those
derivatives. I would hope the licensor himself would make that clear, but
many don't. AFAIK, most licensors expect the second alternative when they do
dual licensing under an open source and a commercial license.

Which of those interpretations applies to the "GPLv2 or later" statements
found scattered in software around the world? 

Clearly, any licensee can choose to accept those works under the GPLv2 now
or GPLv3 now. This doesn't mean that licensees have to perform some
confusing union or intersection of the set of license provisions of GPLv2
and GPLv3 to determine what they can or cannot do with the work. The
original choice was "GPLv2 or later", so choose now, and choose differently
later if you want to. [Note that I do not believe this to be the same issue
as the one addressed by Chris Travers: This dual licensing scenario has
nothing to do with combining GPLv3 works with GPLv2 works and expecting them
to be compatible. License compatibility must be judged differently than dual
licensing by someone who owns the copyright or has permission to do so.]

As for forking a "GPLv2 or later" project into a "GPLv3 only" project, I
don't think that would be allowed unless the original licensor makes that
choice clear in something more specific than a "GPLv2 or later" statement. 

In a world where licensors' intentions aren't always clear, how would you
expect the courts to interpret the word "or" in simple "GPLv2 or later"
statements?

/Larry



> -----Original Message-----
> From: John Cowan [mailto:cowan at ccil.org]
> Sent: Monday, December 03, 2007 8:57 AM
> To: Ben Tilly
> Cc: Wilson, Andrew; License Discuss
> Subject: Re: When to evaluate dual licenses (was: license categories, was:
> I'm not supposed to use the ECL v2?)
> 
> Ben Tilly scripsit:
> 
> > I have a sneaking suspicion that I've just been asked to stop reading.
> >  But I have to ask.  Why would this be axiomatic?
> 
> An axiom A of a logical system S is a statement that is not proved
> (ideally cannot be proved) in S, such that other statements in S
> logically depend on the truth of A.
> 
> Thus, the rest of Andrew's argument depends on this statement, and
> if you deny it, the rest of his argument is thereby vitiated.
> 
> > In other words the GPL v3 makes it clear that accepting the code under
> > the GPL v3 license does not invalidate the permissions you get from
> > all other licenses that may apply to the code.  (Even though they are
> > not yet written!)
> 
> This comes back to my original claim: that if you received code under a
> dual license, you have all the powers granted by either license;
> in this case, the power to issue your derivative work under the GPLv2.
> 
> --
> John Cowan                                   cowan at ccil.org
>         "You need a change: try Canada"  "You need a change: try China"
>                 --fortune cookies opened by a couple that I know