Re: ad hoc license: is it DFSG-conformant ?

[Ben Finney <ben+debian@benfinney.id.au>]

Ian Jackson <ijackson@chiark.greenend.org.uk> writes:

> Ben Finney writes ("Re: ad hoc license: is it DFSG-conformant ?"):
> > One significant lack is that the permissions do not include explicit
> > permission for a recipient to license the work to third parties
> > under the same conditions. This fails DFSG §3.
>
> Such a sublicensing permission is unnecessary since the licence (as
> any Free licence must) gives third parties the necessary permission
> directly.

Yes, I agree that any free-software work must have license granted to
redistribute to others under the same conditions.

What wasn't clear to me was any explicit permission granted to do that,
which is why I came to the conclusion the work is non-free.

> To be more concrete, in this case we are imagining a Debian derivative
> (Knoppix, say) redistributing a modified version of Debian's modified
> version of nauty.

Thanks, a concrete case is helpful.

> For this to be OK, Debian needs:
>
>  - permission from upstream to modify and redistribute modified
>     versions.  This is granted.

Yes.

The Debian Project also needs the license to not be exclusive to Debian;
this requirement is also met.

> Knoppix needs:
>
>  - permission from upstream for Knoppix modify and redistribute the
>     modified versions.  This is granted directly to Knoppix by
>     upstream in thier licence.

I think upstream don't have the exclusive power to grant license to
Knoppix in the modified versions; that's for the copyright holder in
those modified versions.

Let's say that a Debian recipient, Carol, modifies the work such that
they now also hold copyright in the modified work.

Now both upstream and Carol hold copyright in the modified work.

As you say, upstream have granted Knoppix license in the work, but
that's in the work prior to Carol's modifications. Knoppix needs license
in the work as modified by Carol, and so needs license granted by Carol
also.

So how does Carol have permission to extend that license on the modified
work? What in the grant Carol received lets her do that?


Mind you, I note the same issue in the BSD 3-clause and 2-clause texts
(which combine grant of license, with license conditions). Unlike
typical grants for GPLv3, Apache License 2.0, and Expat license grants,
the BSD licenses don't explicitly grant permission to redistribute under
the same license.

So I'm grateful for the concrete example, and am re-assessing my
position; it's more likely my conclusion is incorrect. I would like to
know exactly where — i.e. what in my above reasoning is incorrect.

-- 
 \      “The opposite of a correct statement is a false statement. But |
  `\     the opposite of a profound truth may well be another profound |
_o__)                                              truth.” —Niels Bohr |
Ben Finney