[Debichem-devel] ELPA license and packaging

[Michael Banck]

Hi,

thanks for the answer.

On Sun, Nov 04, 2012 at 12:42:18PM -0500, Volker Blum wrote:
> First, I am not a legal expert and can not simply speak for the whole
> of the ELPA consortium.
 
Of course.

> ... but I know what the intent of that modification was. You are
> right, the concern was that third parties could unilaterally take the
> code and refuse to license modifications in a form that is compatible
> with the original license.
>
> I am not quite sure how our modification would break compatibility
> with GPL, though?

The GPL is a "viral" license.  Thus, any GPL'd work needs to be
implictly or exlicitly under the GPL, including its dependencies (the
code which gets linked into the executable, either via object files or
shared libaries).

In practise, this usually means an implicit relicensing of the non-GPL
parts to the GPL, if that is allowed.  In order to allow this, the LGPL
includes the clause you removed, which makes ELPA non-compatible in our
reading.

If you or your coworkers have a different understanding, I can ask the
license experts of the Free Software Foundation about this.

> How would distribution under the original LGPLv3 solve that problem?
> Does that no longer contain the clause that anyone else can
> redistribute their changes GPL-only - or would that simply reinstate
> the clause in question?
 
Indeed, it would reinstate this problem.  However, if our analysis that
your additional clauses make the ELPA license incompatible to the GPL is
correct, it would be far the lesser of two evils - a slim chance GPL'd
code might not flow back versus GPL'd projects cannot use ELPA at all
legally.

Just as a data point: I've been doing Debian packaging and the licensing
stuff which goes along with it for a dozen years now and this is the
first time I heard about your concerns let alone saw it happen. 

I would think in practise, the chances are very slim you are losing
contributions that way.  Any project which is licensed under the GPL is
a Free Software project by definition and maliciously withholding their
modifications (by explicitly not licensing them under the LGPL) so you
cannot use them would be ethically questionable similar to not citing
somebody else's work in an academic paper, e.g.

Indeed, I see two probable ways to use ELPA: (i) include the code
verbatim in a GPL'd project (so it gets built and linked along with the
rest of the code) and (ii) dynamically link to a shared version of the
ELPA library, possibly shipping the ELPA library as-is externally for
the convenience of the users.  In both cases, it would take the actual
effort to remove your LGPL copyright notices in order to explicitly mark
modifications as GPL only.

Unless you or your coworkers did have bad experiences due to the problem
you try to solve, I would suggest you take the benefit of the doubt and
trust the Free Software and scientific community to send back any
changes they do and/or at least relicense their changes to the LGPL for
your use.

Also note that theoretically there is another way out: You could license
ELPA under the GPL.  This would make sure any modifications will be
usable by you.  Of course, on the other hand it would also mean that
only projects with a license compatible to the GPL will be able to use
ELPA.

In summary, our recommendation would be to simply use the LGPLv3 and (if
you insist on that version) just remove the "or any later" version from
the copyright boilerplate (in order to satisfy the other clause you
added) and/or explicitlay say in a README file or so that the license is
LGPLv3 (and no later version) and let the (improbable) rest be sorted
out by diplomacy and peer pressure.


Best regards,

Michael