Reading Groaklaw I happened to know about “Potential Defenses of Implied Patent License Under the GPL“. a must read for people who thinks that GPLv2 is silent about patents.
Laura Majerus, OSI Director of Legal Affairs and Partner at Fenwick & West, previously wrote “Patent Rights and Open Source – can they co-exist?“, already containing some interesting spots on the subject:
Against software patent by kianee
Setting aside any arguments that the Preamble of the GPL is somehow not a part of the license, it seems clear that an author or modifier who distributes software under the gpl cannot assert his patent rights against subsequent users and redistributors of the GPL’d software. Thus, there is
at least an implied license to those who receive the GPL’d software in any patents covered by the software.
Why then, would anyone want to obtain a patent on an invention that is going to be distributed under the GPL?
There are several reasons:
- the author may plan to license the patent to others to produce a revenue stream
- the author may want to assert his[/her] patent rights against redistributors who do not conform to the GPL license terms (for example, by failing to redistribute under the GPL)
- the author may want to have patent rights to use as an offensive or defensive weapon against infringers who are not using the GPL’d software and
- the author may plan to also distribute a non-GPL’d version of the software.
According to one reasonable interpretation, the GPL only precludes the patentee from asserting his [/her] rights against people who are practicing the invention by using his[/her] GPL’d software. People who independently create other software are not subject to this implied license. As an aside, it seems that the author could assert his[/her] patent rights against a competitor who is himself releasing independently developed software under the GPL, as long as it is not based on the original author’s distribution. The fact that the infringer himself distributes under the GPL is irrelevant as to whether he[/she] is infringing patents of others. The original author has not given permission for his[/her] competitor to use the patented technology.
The author could sue people implementing his/her patents without using his/her GPLed implementation. Infringing activity falling outside the GPL scope are, in this perspective, subjected to patent infringement suit.
The follow up article analyzes in more depth the impact of the GPL on the patent rights of the patentee, and various implied license theories that users of GPL’d software could use in defense against a patent suit.