compatibility Re: License committee report for January 2008

Alexander Terekhov alexander.terekhov at
Tue Jan 29 12:48:06 UTC 2008

On Jan 29, 2008 12:05 AM, Ben Tilly <btilly at> wrote:
> On Jan 28, 2008 12:50 PM, Alexander Terekhov
> <alexander.terekhov at> wrote:
> > On Jan 28, 2008 9:33 PM, Ernest Prabhakar <ernest.prabhakar at> wrote:
> > > Hi Alexander,
> > >
> > > > Really? And that would mean what, exactly?
> > >
> > > The short answer is that we all would like to see the fewest number of
> > > incompatible licenses in the world.  The GPL/LGPL's incompatibility
> > > with certain other licenses is accepted as a "fact of life" by most
> > > open source developers, but that's no reason to encourage/enable
> > > additional incompatibilities.
> > >
> > > Beyond, I'm afraid I've completely lost track of the argument.  It
> > > would help if you could reframe your concern in the form of a Q & A,
> > > so we can document any discussion in the FAQ.
> >
> > Q1) What does "compatibility" mean in the context of licensing?
> >
> > A1) Well, in the GNU Republic, it means ability to "relicense" under
> > the GNU GPL. For example, the LGPL is "compatible" with the GNU GPL
> > thanks to its GPL relicensing clause:
> >
> >
> I like the question, but not the way you put the answer.  Here are a
> series of questions and answers on this topic.
> -----
> Q1) What does "compatibility" mean in the context of licensing?
> A1) Two licenses are compatible if their terms allow you to create,
> modify and distribute software that includes code under each license.
> In general permissive licenses tend to be compatible with other
> licenses and restrictive ones do not.  For example it is easier to
> include code under the MIT in other projects than it is to include
> code that is licensed under the GPL v2 or later.
> Q2) Can I freely include code in my project that is under a compatible license?
> A2) No.  Compatibility just means that you can create code that
> derives from both.  However the combined result must respect both sets
> of copyright terms.  Therefore including code under another license
> may require you to change your own license terms.
> In general projects that use a permissive license (such as the MIT
> license) need to be careful when including code, but their code can be
> widely reused, while projects that use a restrictive license (such as
> the GPL) can use code from other projects but their code cannot be
> reused as widely.  This directionality can be a source of conflict
> between different developers and projects.
> Q3) What is GPL compatibility?
> A3) An important special case of license compatibility is
> compatibility between the GPL v2 or v3 and anything else.  Given the
> GPL's restrictions on sublicensing, it is usually only compatible with
> another license when code under the other license can be relicensed
> under the GPL.
> The OSI does not issue opinions on the compatibility of particular
> pairs of licenses.  However the Free Software Foundation does issue
> opinions on whether specific licenses are GPL compatible.  Their
> licensing page is at
> -----
> The key goal that I had in phrasing that was to be accurate, fair and
> impartial while not hiding potentially divisive issues.

Really? But right from the start you're jumping to the conclusion that
allowance is somehow needed "to create, modify and distribute software
that includes code under each license".

Statutory allowance to distribute under 17 USC 109 aside, consider the
following precedent regarding creation and modification:

Apart from that precedent, consider also the following more general
discussion regarding software combinations:

Finally, regarding the fascinating concept of "GPL compatibility" as
you've explained it, consider this:

A successful misuse defense bars the misuser from
prevailing against anyone on an action for infringement
of the misused intellectual property, even against
defendants who have not been harmed or affected by the

The misuse doctrine was judicially created, first in the
patent context. Only recently has the misuse doctrine been
extended to copyrights, building on the rich misuse history
in the patent law.[77] Importantly, most courts have found
misuse without requiring a finding of antitrust liability.
[78] Thus, market power is unnecessary, as is any analysis
of the competitive and anticompetitive impacts of the

The courts have yet to analyze a copyleft provision for
misuse, but the courts have addressed an analogous
provision—the grantback. A grantback provision requires
that a licensee of intellectual property grant back to
the licensor a license or ownership in creations made by
the licensee. The typical grantback provision requires
that the licensee give the licensor a nonexclusive license
to any improvements or derivatives that the licensee
creates based on the original licensed property. The idea
is that the licensee would not have been able to make the
improvement or derivative without permission of the
licensor or at least access to the original; thus, the
licensor should not be blocked by an improvement or
derivative he and his intellectual property helped create.
Giving the license back encourages licensors to license,
since it mitigates the risk of becoming blocked by
derivative intellectual property. Like a grantback,
copyleft requires the licensee to license back its
improvements. The copyleft provision is more expansive,


Although grantbacks have not come up in the copyright
misuse arena, they have in the patent context—and as we
have seen, the patent misuse cases form the underpinning
for the copyright misuse doctrine. Courts have found that
grantback clauses extending to improvements are not misuse,
because the licensee in some sense developed the
improvement with the help of the original patent. Where
grantback clauses extend to preexisting or unrelated
patents, however, courts have found patent misuse. Where
"the scope of [licensee's] 'improvements' and inventions
required to be assigned to [the patent licensor] extended
far beyond the scope of [the] basic patent [licensed by
licensor] the effect was to extend unlawfully its monopoly
and thus result in patent misuse."[80] Plainly, the Patent
Act does not give the patent owner rights to other unrelated
patents, and using a patent to obtain such rights exceeds
the scope of the patent.

Similarly, the Copyright Act's grant of rights does not
extend to unrelated works or preexisting (and therefore
necessarily nonderivative) works, and using the copyright
license to extract such rights exceeds the scope of the
copyright grant. This may constitute copyright misuse. A
license to a copyrighted work on condition that any work
with which it is combined or shares data must be licensed
back to the licensor—and the entire world—on the specific
terms the licensor mandates, is beyond the scope of the
copyright in the originally licensed work. Yet this is
what the GPL apparently requires. The copyleft provision
purports to infect independent, separate works that are
not derivative of the open source code, and requires
that such independent works be licensed back to the
licensor and the entire world under the GPL. The Copyright
Act does not give the copyright owner rights to such
independent nonderivative works. Attempting to extract
such rights exceeds the scope of the copyright. The fact
that the GPL mandates that the license be free and open is
irrelevant; as explained above, misuse doctrine does not
require an analysis of market share, or a weighing of the
competitive and anticompetitive effects of the provision.

If the copyleft provision constitutes misuse, then the
plaintiff's copyrights in the open source program are
unenforceable until the misuse is purged.[81] As a result,
at least with respect to the code contributed by any
plaintiff, the defendant (and anyone else) could infringe
the copyright with impunity, including taking the code
private for his own commercial ends.[82]

Attribution: "Christian H. Nadan, Director and Associate General
Counsel, Sun Microsystems, Inc., and Adjunct Professor, University of
California Berkeley Boalt Hall School of Law".


"Because of their informal and diffuse nature, open source groups are
vulnerable to theft of their intellectual property. That theft, in the
form of copyright infringement, happened in this case, and Jacobsen
sought a preliminary injunction to enjoin Katzer and KAMIND's


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