Patents and the GPL

[Alexander Terekhov]

Please help me to sort this out. Apache says "legal limbo". I 
suspect that this is nothing but yet another episode in the 
"FSF Comedy" saga. I also don't quite understand the "You may 
add Your own copyright statement..." provision in section 4 
of the Apache License.

TIA... and enjoy it. ;-)

http://www.apache.org/licenses/GPL-compatibility.html

Apache License v2.0 and GPL Compatibility 

A lot of noise has been made recently about this brief 
comment that was placed on the Free Software Foundation's 
license comments page on 18 Feb 2004: 

The Apache Software License, version 2.0 

This is a free software license but it is incompatible with 
the GPL. The Apache Software License is incompatible with the 
GPL because it has a specific requirement that is not in the 
GPL: it has certain patent termination cases that the GPL 
does not require. (We don't think those patent termination 
cases are inherently a bad idea, but nonetheless they are 
incompatible with the GNU GPL.) 

After spending a couple hours on the phone with the FSF, we 
have a better understanding of the particular interpretation 
of the GPL that might lead one to construe the following: 

1. granting an explicit patent license causes any implicit 
patent licenses to be null and void; 

2. revoking that explicit patent license causes the person 
who is claiming infringement of their patent to lose the 
patent rights that would otherwise have been attained via 
the GPL's implicit rights; 

3. loss of patent rights means loss of right to use; 

4. GPL section 7 allows a patent owner to claim infringement 
of a patent within a GPL'd work and continue to distribute 
that work as GPL up until a third party imposes a restriction 
on the rights of others to distribute (i.e., until a 
judgment or injunction is placed on the work). 

5. GPL section 6 saying "You may not impose any further 
restrictions on the recipients' exercise of the rights 
granted herein" does not apply to patents because the 
"rights granted herein" are only copyright. 

This is our current understanding of the position held by 
the FSF; whether or not our understanding is correct has 
not yet been confirmed. 

Note that this is contrary to our previously stated belief 
that the GPL does forbid the continuing use of a GPL'd work 
by an entity that has claimed the work contains infringement 
of their own patented technology. Apparently, it is okay for 
the distribution and use to continue up until a judgment or 
injunction has been issued because the FSF does not believe 
a claim of patent infringement amounts to a restriction on 
the rights of others to redistribute, and the constraint on 
further restriction applies only to those rights listed 
within the GPL itself (copyright). 

Thus, it is conceivable that an entity owning a patent that 
is believed to be applicable to a GPL'd work may continue 
to distribute that work as GPL even after they have made an 
infringement claim, up until the point where that patent is 
successfully used to hinder distribution of the work beyond 
that provided by the GPL, at which point they would have the 
choice of either terminating their own distribution under 
the GPL or declaring something like "this patented 
technology may be used royalty-free if the embodiment is 
distributed under the GPL." 

As such, it finally makes some sense as to why the FSF claim 
of incompatibility was made. However, the above is based on 
the assumption that a patent exists within the work, the 
assumption that implied patent licenses on the GPL-covered 
derived work would be compromised by an explicit patent 
license within one of its parts, and the assumption that an 
implied patent license is capable of being extended to the 
making of new or modified copies of the work by someone other 
than the patent owner. In any case, we do not believe that a 
work which has no licensed patents from contributors could 
ever be subject to the above restrictions, and thus it is 
the presence of a successfully enforced patent that causes 
incompatibility and not the license itself. 

The Apache Software Foundation considers this issue to be 
in legal limbo, at least until we get a definitive answer 
regarding the survivability of implied patent licenses. We 
are still working with the FSF in order to resolve the 
issue, which may result in future changes to either or both 
of our licenses. In the mean time, the FSF requests that 
you do not consider the two licenses to be compatible. The 
Apache Software Foundation believes that you should always 
try to obey the constraints expressed by the copyright 
holder when redistributing their work, even when those 
constraints may be unclear. In the future, we hope that 
the FSF will find a way to express their license terms 
such that they are understandable by recipients of the 
license, rather than requiring interpretation of the 
people who wrote it. 

Background 

GPL compatibility is defined by the FSF, on that same 
page, as: "This means you can combine a module which was 
released under that [compatible] license with a GPL-
covered module to make one larger program." Compatibility 
is enforced within the GPL by section 2b: 

2b) You must cause any work that you distribute or publish, 
that in whole or in part contains or is derived from the 
Program or any part thereof, to be licensed as a whole at 
no charge to all third parties under the terms of this 
License. 

and reinforced by section 6: 

6. Each time you redistribute the Program (or any work 
based on the Program), the recipient automatically receives 
a license from the original licensor to copy, distribute or 
modify the Program subject to these terms and conditions. 
You may not impose any further restrictions on the 
recipients' exercise of the rights granted herein. You are 
not responsible for enforcing compliance by third parties 
to this License. 

The Apache Software Foundation is well aware of these 
clauses and their purpose under copyright law: to ensure 
that code distributed under the terms of the GPL remains 
under the GPL. We have no desire to change the terms 
under which GPL-covered software is distributed. However, 
we do not share the same goals as the Free Software 
Foundation. Our goals are focused on the support of 
collaborative development. The only things we desire from 
a license are protection of our developers from frivolous 
lawsuits and giving everyone the right to use our code 
however they wish, even when they redistribute our code 
in non-open-source products. 

In this case, we would like to enable people who are 
producing GPL-covered products to use some of the software 
libraries that we create and distribute under the Apache 
License. That is one of the reasons we included the 
following in section 4 of the Apache License: 

You may add Your own copyright statement to Your 
modifications and may provide additional or different 
license terms and conditions for use, reproduction, or 
distribution of Your modifications, or for any such 
Derivative Works as a whole, provided Your use, 
reproduction, and distribution of the Work otherwise 
complies with the conditions stated in this License. 

In order to protect our users and contributors against 
some forms of patent litigation, we also include the 
following explicit patent license from our contributors 
to the recipients of the work in section 3 of the Apache 
License, along with a termination clause for reciprocity: 

3. Grant of Patent License. Subject to the terms and 
conditions of this License, each Contributor hereby 
grants to You a perpetual, worldwide, non-exclusive, 
no-charge, royalty-free, irrevocable (except as stated 
in this section) patent license to make, have made, use, 
offer to sell, sell, import, and otherwise transfer the 
Work, where such license applies only to those patent 
claims licensable by such Contributor that are necessarily 
infringed by their Contribution(s) alone or by combination 
of their Contribution(s) with the Work to which such 
Contribution(s) was submitted. If You institute patent 
litigation against any entity (including a cross-claim or 
counterclaim in a lawsuit) alleging that the Work or a 
Contribution incorporated within the Work constitutes 
direct or contributory patent infringement, then any 
patent licenses granted to You under this License for 
that Work shall terminate as of the date such litigation 
is filed. 

Section 7 of the GPL says: 

7. If, as a consequence of a court judgment or allegation 
of patent infringement or for any other reason (not limited 
to patent issues), conditions are imposed on you (whether 
by court order, agreement or otherwise) 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. For 
example, if a patent license would not permit royalty-free 
redistribution of the Program by all those who receive 
copies directly or indirectly through you, then the only 
way you could satisfy both it and this License would be to 
refrain entirely from distribution of the Program. 

We interpreted this to mean that you cannot redistribute 
software that is covered by a patent wherein the patent is 
not licensed free for everyone. In fact, a more narrow 
interpretation is that you cannot redistribute the software 
once a restriction has been imposed that prevents 
redistribution to everyone under the GPL. What we hadn't 
considered is that the patent might be owned by an entity 
like the FSF and licensed exclusively to GPL implementations. 
We still don't understand how such a patent could be added 
to the ASL2 work in the first place, but if it were added 
and would be subject to the termination clause and was not 
available for use separately under the GPL, then it might 
affect the redistribution of the combined GPL work when 
distributed by or through the patent owner. 

No, we don't have any patents 

The Apache Software Foundation is a nonprofit organization 
that is dedicated to open source software development. We 
never knowingly incorporate patented technology in our own 
products unless such technology has been offered free for 
everyone. 

Please note that this discussion only benefits third parties 
that produce GPL-covered products. The Apache Software 
Foundation does not allow its own projects to distribute 
software under licenses more restrictive than the Apache 
License, and the Free Software Foundation does not 
distribute software under the Apache License. 

The ASF will not dual-license our software because such 
licenses make it impossible to determine the conditions 
under which we have agreed to collaborate on a collective 
product, and are thus contrary to the Apache spirit of 
open, collaborative development among individuals, 
industry, and nonprofit organizations. 
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