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

[Ben Tilly]

On Dec 3, 2007 9:20 AM, Wilson, Andrew <andrew.wilson at intel.com> wrote:
>
> Ben Tilly wrote:
> >Andrew Wilson wrote:
> >> This is a very interesting question.  Let's assume, for purpose of
> >> discussion, that
> >> it is axiomatic that the license of a derivative work of GPL code ==
> >> effective license of the
> >> original GPL code.  {Yes, I know, not everyone accepts this.  Stop
> >> reading now
> >> if you don't.}
> >
> > I have a sneaking suspicion that I've just been asked to stop reading.
> > But I have to ask.  Why would this be axiomatic?
>
> Let me try a more precise formulation: it is axiomatic that the
> license of a derivative work of GPL code must be a license which
> is permitted by the license of the original GPL work.  Better?

Yes.

Now look at the GPL v2 or v3 and tell me what restrictions it places
on what permissions I am allowed to put on my contribution.  By my
reading there is a minimum restriction - I must allow my contribution
to be licensable under the GPL.  But there is no restriction saying
that I cannot be more generous still.  And, of course, by default I am
allowed to be as generous as I want with my own copyrighted work.
(Because I own the copyright!)

Furthermore while it does not explicitly say that licensing a
contribution GPL v3 or better is allowed, it is clear from the license
that it is intended that this be possible.

> Just trying to prevent this thread from being sidetracked by those
> who question the validity of GPL-imposed licensing constraints on
> derivatives.
> For anyone of that mindset, this entire thread is presumably moot.

Whew.  I'm not of that mindset. :-)

> { ... discussion follows about permitted licenses of GPLv2-or-later
> derivatives ...}
>
> > My theory is that you accept the licensed code under GPL v3 and
> > release your modifications as GPL v3 or later.  That makes the license
> > on the combined work be the intersection of the original (GPL v2 or
> > later) and your code (GPL v3 or later) which is GPL v3 or later.
>
> Hold on a minute, partner.  If you have accepted the V2-or-later
> licensed code
> under V3 and combined it with V3-or-later additional code, the
> intersection
> of these licenses is V3-only.  I do not see how you can both
> "accept the licensed code under GPL v3" and then immediately revert
> to the original V2-or-later inbound license.

There is no conflict.  Let's take this in steps.

I have accepted the code under the GPL v3.  I am bound by the GPL v3.
Are we agreed about this?

I am allowed by the GPL v3 to license my contribution GPL v3 or later.
 Are we agreed about this?  (Note that my so licensing it does not
change *my* obligations one bit, I still have to follow the GPL v3.)

The GPL v3 allows me to distribute the modified result to a third
person, say Carol.  Of course it does so under its terms, which I am
obliged to follow.  Are we agreed about this?

Carol has received code from me.  From the copyright licenses she has
been offered part of it under GPL v2 or later from the original
author, and some modifications (from me) under GPL v3 or later.  Are
we agreed on this?

As section 10 of the GPL v3 makes clear (there was a similar section
in the GPL v2, and in fact I understand that this section is merely a
restatement of copyright law), Carol's acceptance of the license is in
no way, shape or form contingent on my acceptance of the license.
Therefore she is allowed to accept the permissions of the GPL v3.  If
a GPL v4 is out, she is allowed to accept that set of permissions
instead.  If she can track down all of the copyright holders and
negotiate her own terms, she can accept it under any copyright license
she can get us to agree to.

In short I can take code licensed "GPL v2 or later", make a
modification and license that modification "GPL v3 or later", then
give it to someone and at that point the code really IS GPL v3 or
later.

Cheers,
Ben