Subject: Re: legal issues under GPL
From: John Cowan <>
Date: Fri, 7 Mar 2003 07:04:37 -0500 (EST)

Chris D. Sloan scripsit:

> Now, here's my first uncertainty:  I think that the GPL requires that
> AP also be under the GPL,

Yes.  Since A is under the GPL, all derivative works must be under the GPL
as well.

> and it may also require that P be under the
> GPL too.  I'm not exactly sure.

No.  What is required is that P's license not impose any restrictions
other than those imposed by the GPL.  The BSD license, for example,
requires only that the copyright and BSD license text be kept with the
licensed work, which are also GPL requirements, so there is no problem
with P's license being the BSD.

> Since P (or AP) is under the GPL, Bob shouldn't have any more right to
> relicense it under his dual license than Charlie would to relicense A
> under Charlie's Commercial License.
> Is there some magic in the dual license which helps Bob do what he
> wants?  Or does Bob need to get a signed copyright assignment from
> Charlie in order to relicense P (as part of B) under the GPL/BCL dual?

Your analysis is quite correct:  Bob needs to get a license from Charlie
or else a copyright assignment from Charlie.  However, there is a practical
point:  In the U.S. at least, Charlie has very limited remedies if he
has not (as most programmers have not) registered P with the Copyright Office.
They are restricted to actual monetary damages, and it will be very difficult
for Charlie to prove that he has suffered any such thing.

John Cowan     
To say that Bilbo's breath was taken away is no description at all.  There
are no words left to express his staggerment, since Men changed the language
that they learned of elves in the days when all the world was wonderful.
        --_The Hobbit_
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