Reading through Facebook's PATENTS file in its React library and several discussions on Hacker News have left me confused about the implications this file which is included in several open-source libraries made by Facebook.

The primary question is: does losing the license mean the individual or company distributing a product using this library has to stop using React entirely and reimplement their product without it, or does it only affect your ability to defend your own patents that may rely on the patents covering the library?

Additionally, what is the breadth of the phrase "other actions" in the first sentence of the second paragraph? Claim is defined as a "lawsuit, assertion or other action" which sounds extremely broad.


Facebook has amended its PATENTS file in order to clarify the scope of the grant. While their library is no longer the subject of this question, I wouldn't mind an explanation of the actual repercussions of losing a license that has been granted through such methods.

New PATENTS file

  • I wonder what's the point of getting into patents at all - why not simply say "if you (or anyone anywhere near you) sues us (or anyone anywhere near us) for patent infringement, the entire licence is revoked, unless you are countersuing us for suing you for same. Why even pick out patents, rather than just revoking the licence in its entirety? Is it so they can claim the code is open source?
    – Rob Grant
    Apr 16, 2017 at 21:43

1 Answer 1


One reason why this question may have gone unanswered for so long is that it is a pretty complicated one. People who favor open source software have been worried about the impact that patents might have on the freedom to use that software. One response has been to modify open source licensing agreements to require automatic patent licensing by people who contribute to the software. This creates a weird legal landscape where nobody is really clear about what patents are even licensed by the software agreement (e.g. what if PatentCo contributes to the OSS but doesn't clarify which patents it holds and which of those apply to the software).

If we separate the question you posed from the practical and legal issues related to incorporating a mandatory patent license into an OSS agreement, we get this simple question: What happens if you have a patent license and that license terminates? The simple answer is that you can be sued for infringement if you continue to infringe. The more complex answer is that a good lawyer can come up with some defenses. One defense might be to claim some form of patent exhaustion; another might be to claim estoppel. The risk you run, though, is that you are going to be on notice of the patent and of your infringement, so you risk the enhanced damages that are available for intentional infringement. Bottom line: Yours is the kind of question that keeps patent litigators employed. There isn't a firm answer to the abstract question as posed because this is the kind of case where the specifics are going to matter.

As a side note, Facebook's current policy (from the Patents file you linked to) is apparently to have the patent licenses automatically terminate if the licensee challenges the validity of the patents. It is unclear to me based on Medimmune http://www.supremecourt.gov/opinions/06pdf/05-608.pdf whether this provision would survive a challenge.

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