Chapter 6
GPL’s Implied Patent Grant

We digress again briefly from our section-by-section consideration of GPLv2 to consider the interaction between the terms of GPL and patent law. The GPLv2, despite being silent with respect to patents, actually confers on its licensees more rights to a licensor’s patents than those licenses that purport to address the issue. This is the case because patent law, under the doctrine of implied license, gives to each distributee of a patented article a license from the distributor to practice any patent claims owned or held by the distributor that cover the distributed article. The implied license also extends to any patent claims owned or held by the distributor that cover “reasonably contemplated uses” of the patented article. To quote the Federal Circuit Court of Appeals, the highest court for patent cases other than the Supreme Court:

Generally, when a seller sells a product without restriction, it in effect promises the purchaser that in exchange for the price paid, it will not interfere with the purchaser’s full enjoyment of the product purchased. The buyer has an implied license under any patents of the seller that dominate the product or any uses of the product to which the parties might reasonably contemplate the product will be put.

Hewlett-Packard Co. v. Repeat-O-Type Stencil Mfg. Corp., Inc., 123 F.3d 1445, 1451 (Fed. Cir. 1997).

Of course, Free Software is licensed, not sold, and there are indeed restrictions placed on the licensee, but those differences are not likely to prevent the application of the implied license doctrine to Free Software, because software licensed under the GPL grants the licensee the right to make, use, and sell the software, each of which are exclusive rights of a patent holder. Therefore, although the GPLv2 does not expressly grant the licensee the right to do those things under any patents the licensor may have that cover the software or its reasonably contemplated uses, by licensing the software under the GPLv2, the distributor impliedly licenses those patents to the GPLv2 licensee with respect to the GPLv2’d software.

An interesting issue regarding this implied patent license of GPLv2’d software is what would be considered “uses of the [software] to which the parties might reasonably contemplate the product will be put.” A clever advocate may argue that the implied license granted by GPLv2 is larger in scope than the express license in other Free Software licenses with express patent grants, in that the patent license clause of many of those other Free Software licenses are specifically limited to the patent claims covered by the code as licensed by the patentee.

In contrast, a GPLv2 licensee, under the doctrine of implied patent license, is free to practice any patent claims held by the licensor that cover “reasonably contemplated uses” of the GPL’d code, which may very well include creation and distribution of modified works since the GPL’s terms, under which the patented code is distributed, expressly permits such activity.

Further supporting this result is the Federal Circuit’s pronouncement that the recipient of a patented article has, not only an implied license to make, use, and sell the article, but also an implied patent license to repair the article to enable it to function properly, Bottom Line Mgmt., Inc. v. Pan Man, Inc., 228 F.3d 1352 (Fed. Cir. 2000). Additionally, the Federal Circuit extended that rule to include any future recipients of the patented article, not just the direct recipient from the distributor. This theory comports well with the idea of Free Software, whereby software is distributed among many entities within the community for the purpose of constant evolution and improvement. In this way, the law of implied patent license used by the GPLv2 ensures that the community mutually benefits from the licensing of patents to any single community member.

Note that simply because GPLv2’d software has an implied patent license does not mean that any patents held by a distributor of GPLv2’d code become worthless. To the contrary, the patents are still valid and enforceable against either:

any software other than that licensed under the GPLv2 by the patent holder, and
any party that does not comply with the GPLv2 with respect to the licensed software.

For example, if Company A has a patent on advanced Web browsing, but also licenses a Web browsing program under the GPLv2, then it cannot assert the patent against any party based on that party’s use of Company A’s GPL’d Web browsing software program, or on that party’s creation and use of modified versions of that GPL’d program. However, if a party uses that program without complying with the GPLv2, then Company A can assert both copyright infringement claims against the non-GPLv2-compliant party and infringement of the patent, because the implied patent license only extends to use of the software in accordance with the GPLv2. Further, if Company B distributes a competitive advanced Web browsing program that is not a modified version of Company A’s GPL’d Web browsing software program, Company A is free to assert its patent against any user or distributor of that product. It is irrelevant whether Company B’s program is also distributed under the GPLv2, as Company B can not grant implied licenses to Company A’s patent.

This result also reassures companies that they need not fear losing their proprietary value in patents to competitors through the GPLv2 implied patent license, as only those competitors who adopt and comply with the GPLv2’s terms can benefit from the implied patent license. To continue the example above, Company B does not receive a free ride on Company A’s patent, as Company B has not licensed-in and then redistributed Company A’s advanced Web browser under the GPLv2. If Company B does do that, however, Company A still has not lost competitive advantage against Company B, as Company B must then, when it re-distributes Company A’s program, grant an implied license to any of its patents that cover the program. Further, if Company B relicenses an improved version of Company A’s program, it must do so under the GPLv2, meaning that any patents it holds that cover the improved version are impliedly licensed to any licensee. As such, the only way Company B can benefit from Company A’s implied patent license, is if it, itself, distributes Company A’s software program and grants an implied patent license to any of its patents that cover that program.