- The GPL Bargain
- Copyleft and Reciprocity
- Policy Objectives
- The Preamble to the GPL
- GPL as Template
- The GPL Applies to Programs
- Linking to GPL Software
- Copyright Law and Linking
- The LGPL Alternative
- GPL Grant of License
- Access to Source Code
- "At No Charge"
- Other Obligations in the GPL
- The GPL and Patents
- Accepting the GPL
The GPL and Patents
Nobody is quite sure what effect software and business method patents will have on open source software. That is because patent problems often arise from unexpected quarters. A person nobody heard of may claim that software infringes his or her patent. Suddenly software embodying that patent cannot be made, used, or sold absent a license from the patent ownerunless, of course, the patent can be designed around and similar functionality accomplished in a different way.
It may thus happen that open source software that was previously free is no longer so. But that conclusion is here just a vague abstraction. Which software and which patent, and what effect on software freedom, is a mystery until it actually happens.
The GPL deals with such potential patent claims in a philosophically consistent way. If and when a valid patent claim by a third party prevents a GPL licensor from making, using, or selling the software, such software will no longer be free (in the GPL's sense of that word) and the software can no longer be distributed under the GPL. Here is the provision:
If, as a consequence of a court judgment or allegation of patent infringement..., 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.... (GPL section 7.)
This leaves undefined just what "pertinent obligations" one might incur as a "consequence of court judgment," and leaves to later analysis what "obligations under this License" might be contradicted by the court judgment. The provision clearly means, though, that it will take more than the threat of patent infringement to invoke this provision. An actual patent dispute has to be alleged and either litigated or settled.
At the end of section 7, the GPL describes this patent provision not as a new provision but as "a consequence of the rest of this License." And so it is important to ask whether this form of self-imposed restriction on licensing in the face of a third party patent claim is an inevitable consequence of open source licensing in general or something unique to the GPL. It is particularly instructive that only the GPL has this provision, and that many other important open source licenses have very different patent defense provisions that don't require subsequent licensees to forgo their rights to create and distribute derivative works.
The only obligations a licensee accepts under the GPL are (1) the reciprocity obligation and (2) obligations regarding the integrity of the original authors. It is difficult to see how a court judgment regarding a patent would prevent either of these two obligations from continuing to be met.
I will describe in more detail in a later chapter on open source litigation that there are really only two significant consequences of civil litigation about a software license: an injunction or an economic penalty. As to injunction, whatever the injunction you must obey it; if a court orders you to stop making, using, or selling a patented invention, you must do so. As to economic penalties, if a court orders you to start paying royalties or to pay royalties for past infringement, you must do so. (You agree to accept those risks; the GPL's warranty provision, similar to those in most other open source licenses, provides no warranty of noninfringement.) The risk from patent infringement is the same whether you use the GPL, any other open source license, or indeed any proprietary license.
If a court order requires that you stop distributing derivative works unless you pay a license fee to a patent holder, you may elect to stop distributing derivative works or to pay the fee. The at no charge language of the GPL's reciprocity provision may prevent you from recovering that cost, but by itself it doesn't prevent you from continuing distribution if you're willing to do so at your own cost.
Patents are a local problem. Patents are awarded nationally; what is patented in one country may be free to use in other countries. The GPL acknowledges this by allowing licensors to continue to license their works in the geographical regions where the patents don't apply:
If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted inter-faces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded.... (GPL section 8.)