GPL and LGPL question

Seth David Schoen schoen at
Tue May 18 22:09:05 UTC 1999

Pat St. Jean writes:

> I've got a program foo.  I want program foo to do bar.  I download a GPL'd
> library quux that does bar.  I incorporate it into my program foo.  By the
> terms of the GPL, foo must now be distributed under the GPL (2b of the
> GPL).  Isn't that in conflict with #3, which says "...must allow them to
> be distributed..."?

No.  You've just discovered the so-called "viral" nature of the GPL, and
the issue of conflicting licenses.

GPL 7 addresses this question:

	If ... for any ... reason (not limited to patent issues), conditions
	are imposed on you that contradict the conditions of this License,
	they do not excuse you from the conditions of this License.  If you
	cannot distribute so as to satisfy simultaneously your obligations
	under this License and any other pertinent obligations, then as a
	consequence you may not distribute the Program at all.

The GPL's requirement that anything that wants to use GPLed code must
itself be GPLed is entirely deliberate.  One of the purposes of the GPL
is to expand the amount of free software in existence: "To protect your
rights, we need to make restrictions [which] translate to certain
responsibilities for you if you distribute copies of the software..."
You can read some of Richard Stallman's essays at
"" for further explanation of this strategy.

Some people think this is a feature and some people think it's a bug,
but it doesn't create any conflict with the Open Source Definition.

> What I'm getting at is that #7 says that one cannot require that an
> additional license be executed between parties.  LGPL clause 3 allows
> anyone, without the consent of the owner of the code, to change the
> licsensing of the code.

That's not in itself a problem, because the original author of the code
consented to that condition by putting the license under the LGPL rather
than some other Open Source license.  If you don't want people to be
able to take your LGPL code GPL, don't develop under the LGPL.

But I do think you've identified a real problem, because OSD 7 doesn't
allow rights initially granted by an Open Source license to be narrowed
by subsequent redistribution.  But the procedure in LGPL 3 _does_ allow
those rights to be limited that way.

> It also seems to violate OSD #3 in that if someone decides to exercise
> LGPL clause 3, they cannot be distributed under the same terms as the
> license of the origional software (LGPL).

Again, the license must allow redistribution under the same license, not
require it.  If the license doesn't require it, it's possible that some
derived works will no longer be Open Source (as with the MIT and X licenses)
or at least no longer under the same Open Source license (as with the

                    Seth David Schoen <schoen at>
      They said look at the light we're giving you,  /  And the darkness
      that we're saving you from.   -- Dar Williams, "The Great Unknown"  (personal)  (CAF)

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