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MPL and patents

The Mozilla Public License (MPL), version 2.0, contains a broad patent grant and a retaliation clause that is similar to that of the Apache License 2.0. This article is part of the series on patent clauses in software licences.

MPL 2.0

The text of MPL-2.0 is available at

Retaliation clause

MPL-2.0 contains a retaliation clause in section 5.2, similar to that of the Apache License 2.0. This replaces and simplifies the retaliation clause that was section 8.2 in MPL-1.1.

5.2. If You initiate litigation against any entity by asserting a patent infringement claim (excluding declaratory judgment actions, counter-claims, and cross-claims) alleging that a Contributor Version directly or indirectly infringes any patent, then the rights granted to You by any and all Contributors for the Covered Software under Section 2.1 of this License shall terminate.

One goal of the MPL-2.0 patent clause was to be compatible with that of the Apache License 2.0.[1]


MPL-2.0 also includes a fairly narrow patent grant which covers just slightly more than a contributor's contribution. It covers the contribution plus any functionality which which the software gains because of the contribution.

The first part of the grant is section 2.1:

[2.1] Each Contributor hereby grants You a world-wide, royalty-free, non-exclusive license: (...) under Patent Claims of such Contributor to make, use, sell, offer for sale, have made, import, and otherwise transfer either its Contributions or its Contributor Version.

But this is significantly narrowed by section 2.3:

[2.3] Notwithstanding Section 2.1(b) above, no patent license is granted by a Contributor: (...) [2.3c] under Patent Claims infringed by Covered Software in the absence of its Contributions.

The wording is somewhat ambiguous, and it seems possible to interpret section 2.3 as having almost no effect: it could be read as saying that the patent grant is only valid if the code is there in the software. This would not narrow the grant by much. The presence of the code, anywhere in the software, would still suffice to give the recipients a patent grant for the whole of the software.

However, according to Gervase Markham of the Mozilla Foundation,[2] this is not the correct interpretation. Markham says that 2.3(c) means that MPL-2.0 is like Apache2 and has thus only a narrow grant.


Does that mean that:

  1. For uses where the software would infringe if the contribution was removed, there's no licence. In that case, this grant isn't broad at all. It only covers the functionality which relies on the contribution, not all the functionality of the software.
  2. For people who got the software without the contribution (before it was added or after it was removed), there's no licence. In that case, this does not really narrow the grant.

The difference is quite important. Any help?

  • As far as I can tell, [2.3] is saying that the grant for that specific patent does not apply if the code ("Contribution") covered by said patent is removed (or, in some other way, lacking). This way projects aren't granted patents in perpetuity if the patented code is removed. Both [2.3(a)] and [2.3(c)] seem to convey this idea in different wording. So I believe that this clause is intended to mean your second interpretation, the one you conclude as more normal. Mutoso (talk) 21:49, 31 October 2013 (EDT)
    • Ok, I agree with you for the case where code is later removed. But I'm still trying to figure out if the patent licence granted by [2.1b], which applies to the entire "Contributor Version" (original + contribution) or just the Contribution. Two examples:
      1. Person-A a patented technique in 2005 to make buttons more responsive. She sees version 1 of an application and contributes code in 2009 to make the buttons on one dialog box more responsive, making version 2. Person-B sees the technique in version 2 and applies the same technique to make all the other buttons more responsive in 2010, making version 3. Is the user safe from Person-A's patents when using Person-B's code in version 3? The answer appears to be no: Person-B's code wasn't in Person-A's Contributor Version, so isn't covered by Person-A's licence grant.
      2. Same story, but imagine Person-B developed this technique independently in 2007 and immediately added it to some parts of the software. Section [2.1b] would say that, after Person-A's contribution in 2009, the patent licence she gives covers Person-B's code because it's part of her Contributor Version, but does [2.3c] then take that protection away by excluding coverage of Patent Claims infringed by Covered Software in the absence of its Contributions? I think so. If this is always the case, then section [2.1b] is kinda misleading about the scope of the patent protection.
    • So it seems that in both cases, the user has no patent protection. (A separate question is then: does this matter? Are these situations realistic?) Patent protection clauses should always be as broad as possible, within the limits of how much you are willing to risk scaring away big companies that want to contribute. In these two instances, would giving protection scare away businesses? If not then MPL-2.1 should consider broadening the patent protection for users. Ciaran (talk) 14:27, 1 November 2013 (EDT)

According to MPL2 is like Apache2, not GPLv3 due to 2.3(c). Mike Linksvayer (talk) 09:06, 7 August 2014 (EDT)

MPL 1.1

Section 8:

8.2. If You initiate litigation by asserting a patent infringement claim (excluding declatory judgment actions) against Initial Developer or a Contributor (the Initial Developer or Contributor against whom You file such action is referred to as "Participant") alleging that:

a.   such Participant's Contributor Version directly or indirectly infringes any patent, then any and all rights granted by such Participant to You under Sections 2.1 and/or 2.2 of this License shall, upon 60 days notice from Participant terminate prospectively, unless if within 60 days after receipt of notice You either: (i) agree in writing to pay Participant a mutually agreeable reasonable royalty for Your past and future use of Modifications made by such Participant, or (ii) withdraw Your litigation claim with respect to the Contributor Version against such Participant. If within 60 days of notice, a reasonable royalty and payment arrangement are not mutually agreed upon in writing by the parties or the litigation claim is not withdrawn, the rights granted by Participant to You under Sections 2.1 and/or 2.2 automatically terminate at the expiration of the 60 day notice period specified above.

b.   any software, hardware, or device, other than such Participant's Contributor Version, directly or indirectly infringes any patent, then any rights granted to You by such Participant under Sections 2.1(b) and 2.2(b) are revoked effective as of the date You first made, used, sold, distributed, or had made, Modifications made by that Participant.

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