The GNU General Public License (GPL version 2)
is the slightly modified successor the oldest reciprocal license (the GPLv1).
An overview for further reading on the GPL:
- Die GPL kommentiert und erklärt (Till Jaeger et. al, O'Reilly März 2005)
- Lawrence Rosen on the GPL Chapter 6
- Thomas F. Gordon on general license combatibility
- Lothar Determan - Software combinations as Derivative works?
With a strict view on the
the GPL would be a non-free license.
In GPL section 8, it is permitted to add a clause that could restrict the GPL
to give it's permission only to specific groups, but this would be in conflict with
section 5 of the OpenSource definition.
Fortunately, there is no actual software that makes use of GPL section 8, so all
currently existing GPLd software is compliant to the OpenSource definition.
The GPL is a reciprocal license with a strong Copyleft
The GPL gives patent grants but does it contain rules that help to defend against
The GPL and collective vs. derivative works
FSF (creator of the GPL) is very eager with
explaining that the GPL is not a "contract" but a "license" under US law, see this
For this reason, the GPL may only rightfully contain claims that are permitted by
US Copyright law title 17 paragraph 106
The right to define what's a derivative work is not amongst these grants from
the US Copyright law.
As a result, the definitions for collective and derivative works from the US
Copyright law apply.
So fortunately, most real world issues with the GPL refer to collective works
where independent works just link against each other. This is clearly permitted
by the GPL.
A derivative work is a work made from one or more independent works
and where a modification of significant own creation is added.
Modifications of minor importance/creation are not Copyrightable and do not create
a derivative work but just a variant of the original work.
In a derivative work that matches the definitions from the Copyright law, the GPL
requires the the modifications to be put under GPL.
In contrary to that, a collective work is a work created from the combination of
several independent works.
It is thus obvious that edits of a pure GPL work typically create a derivative work
and that combinations from a GPL work with another work under a different license typically
create a collective work.
The GPL and the community
The GPL is the most successful OSS license but there is few unbiased information
on the GPL available in the net.
Some unbiased information may be found in:
Lawrence Rosen on the GPL Chapter 6
Thomas F. Gordon on general License compatibility.
As these papers explain,
several of the important claims of the GPL are in conflict with the Copyright law
and thus will most likely not stand in court.
For this reason it is questionable whether it makes sense to use a license that
includes restrictions that appear to be useless. Since a few years, there are other
reciprocal (Copyleft) licenses that avoid to make those restrictive claims of
The GPL in collaborative works
The GPL prevents code flow from code under GPL into other works being under different
Note that the GPL still permits collective works and thus allows linking against
other independent works as long as this may be achieved by linking unmodified works or only
slightly modified works.
As the GPL impairs collaboration and as the GPL, does not contain a method to
defend against patent suing,
the OSSCC does not recommend to use the GPL for new projects.
The GPLv3 has been published in June 2007.
The GPLv3 no longer contains claims that are comparable to section 8 of the GPL,
so the GPLv3 is a true OSS license.
The GPLv3 added claims to defend against patent suing.
Unfortunately, the GPLv3 tries to add further restrictions on collective works
and as this is done by using an ambiguous wording, it is expected to create a
high risk to distributors for being sued by authors or Copyright holders.
As the GPLv3 impairs collaboration even more than the GPL,
the OSSCC does not recommend to use the GPLv3 for new projects.
You may contact us by sending mail to: info at osscc.net