Patents are separate from copyright licenses. If you find some source code licensed under GPLv2, MIT, BSD, and many other OSS licenses, then these come with no

Patents are separate from copyright licenses. If you find some source code licensed under GPLv2, MIT, BSD, and many other OSS licenses, then these come with no patent license. It is up to you to find out if any patents covering them exist (by original authors or anyone else), and negotiate a patent license. Or if you live in a country that does not recognise software patents, you can just ignore the issue. So an explicit patent grant, even if terminated if you sue Facebook for patent infringement, is much better than omitting the PATENTS file. The very popular OSS Apache 2.0 license includes the same language to grant a patent license that is terminated if you start a patent lawsuit. Avoid suing Google about Android patents or Microsoft about .NET patents if you are using that software. Overall I think it's a good thing, and if enough open-source projects adopt the same rule, then it could perhaps become a poison pill that stops everyone from enforcing software patents.