The Apache 2.0 patent retaliation clause automatically and permanently revokes your patent license the day you file a lawsuit claiming the licensed software infringes one of your patents. Section 3 of the license pairs a broad, royalty-free patent grant from every contributor with a termination trigger that strips those rights from anyone who uses the software as a weapon in patent litigation.1Apache Software Foundation. Apache License 2.0 There is no warning, no grace period, and no way to undo it.
What Sets the Clause Off
Termination fires when you “institute patent litigation against any entity” alleging that the licensed work, or a contribution within it, constitutes direct or contributory patent infringement.1Apache Software Foundation. Apache License 2.0 Every patent license granted to you under the Apache license for that particular work terminates on the date the complaint is filed. Not when the court rules. Not when the defendant answers. The day the case hits the docket.
Two limits on the trigger are worth pinning down. The lawsuit has to allege that the Apache-licensed work itself, or a contribution within it, infringes your patent. Suing someone over an unrelated patent that has nothing to do with the licensed code does not fire the clause. And the termination reaches only the patent grants for the specific project you targeted. If you use several Apache-licensed projects, the others are not affected.
Counterclaims Count
The clause explicitly includes cross-claims and counterclaims as triggers.1Apache Software Foundation. Apache License 2.0 If someone sues you first and you respond with a counterclaim alleging the Apache-licensed software infringes your patent, you lose the grant. It does not matter that you were defending yourself. The license draws no line between offensive and defensive litigation.
That is a deliberate design choice, and an aggressive one. The Mozilla Public License 2.0 carves out declaratory judgment actions, counterclaims, and cross-claims from its retaliation trigger, so defending yourself does not cost you the license.2Mozilla Foundation. Mozilla Public License Version 2.0 Apache 2.0 offers no such safe harbor. Anyone facing patent litigation involving Apache-licensed code has to think carefully before asserting patent claims about that code in any direction.
What You Lose and What You Keep
The termination is surgical. Only the patent grants under Section 3 are revoked; the copyright license granted under Section 2 survives.1Apache Software Foundation. Apache License 2.0 You can still copy, modify, and distribute the source under the copyright terms. What you lose is the shield against patent infringement claims from contributors whose patented technology is embedded in the code.
The split matters more than it first looks. Open-source software often implements techniques covered by patents. The copyright permission lets you handle the code itself; the patent permission let you use the inventions the code embodies. Losing one while keeping the other puts you in an awkward spot: you can distribute the source, but running it may infringe patents you no longer have a license to practice.
There Is No Cure Period
Apache 2.0 has no mechanism to restore your patent grant once it terminates. No grace period, no notice requirement, no option to withdraw the lawsuit and get your rights back. The moment you file, the grant is gone.
This is a sharp break from the GNU General Public License v3.0, which includes a layered reinstatement path. Under GPLv3, if you violate the license and stop, your rights are reinstated provisionally, and permanently if the copyright holder does not notify you of the violation within 60 days after you stopped, or if you cure a first-time violation within 30 days of receiving notice.3GNU Project. GNU General Public License v3.0 Apache 2.0 has nothing comparable. The permanence is one of the clause’s strongest deterrents and one of its greatest risks.
What Happens If You Keep Running the Code
After the patent grant terminates, you still hold the copyright license, so continuing to use and distribute the code is not copyright infringement. But you no longer have a patent license. If the software practices any contributor’s patented invention, your continued use could be patent infringement, and a contributor would be within their rights to bring a claim. You would have no license to raise as a defense.
The real exposure depends on the project. Some Apache-licensed code implements patented algorithms or protocols; other code may not implicate any patents at all. For projects with contributions from companies that hold significant patent portfolios, losing the grant is a serious liability. Defending a patent suit through trial typically costs hundreds of thousands of dollars or more, before any damages.
Downstream Users Are Not Affected
If a company distributes Apache-licensed software to customers and then triggers the clause by filing a patent lawsuit, the downstream users do not lose their own patent grants. Apache 2.0 operates as a direct grant from each contributor to each user. The termination language targets “You,” meaning the party that instituted the litigation. Everyone else keeps their full rights.
That structure matters for supply chains. If your vendor triggers the clause, your own patent license stays intact because it came directly from the contributors, not through your vendor. One party’s aggressive patent behavior does not cascade through the ecosystem.
How Apache 2.0 Compares to Other Licenses
Not every open-source license handles patent retaliation the same way. The differences shape which risks apply depending on what license covers the code you use.
- Apache 2.0 terminates patent grants immediately and permanently when you file any patent litigation (including counterclaims) alleging the licensed work infringes your patents. No cure period. The copyright license survives.1Apache Software Foundation. Apache License 2.0
- GPLv3 grants a broader patent license covering all patent claims you control for all versions of the work, present and future. Termination for license violations includes provisional reinstatement and a 30-day cure window for first-time violations.3GNU Project. GNU General Public License v3.0
- MPL 2.0 terminates all rights from all contributors, not just patent rights, when you file offensive patent litigation, but explicitly exempts declaratory judgments, counterclaims, and cross-claims.2Mozilla Foundation. Mozilla Public License Version 2.0
- Eclipse Public License 1.0 also includes counterclaims and cross-claims as triggers, but narrower in scope. The clause applies only to claims about the program itself and excludes claims about combinations with other software or hardware.4Eclipse Foundation. Eclipse Public License v1.0
- MIT and BSD contain no patent grant and no retaliation clause. You get no affirmative patent license, so you have nothing to lose through retaliation, but you also have no patent protection to start with.
Apache 2.0 sits in the middle. It is more aggressive than MPL in punishing defensive counterclaims and more targeted than EPL in reaching only patent rights rather than the whole license. For organizations mixing code under several licenses, tracking these differences prevents unpleasant surprises during a dispute.
What This Means for Patent Strategy and M&A
The clause becomes a practical concern during acquisitions, investment rounds, and any moment when a company’s intellectual property is under scrutiny. Acquirers looking at a target company will examine how it uses Apache-licensed code and whether its patents overlap with contributions to those projects. A company that has already tripped the clause for a project it depends on is carrying a patent liability that can affect deal valuation and timing.
Even without a past triggering event, the clause constrains future patent strategy. If your core product relies on Apache-licensed libraries and your patent portfolio covers similar technology, you cannot assert those patents against the licensed software without forfeiting the protection that keeps your own use of it legally safe. Patent-heavy companies need to map patents to products carefully and track which contributions went into which open-source projects. Founders planning to raise capital or pursue an exit are better off documenting open-source usage and contribution history early, because sorting it out during diligence is slower and more expensive.
Litigation planning follows the same logic. Before filing a patent infringement suit, check whether the target software incorporates Apache-licensed components that your own company uses. Filing could wipe out your patent protections for that code, a self-inflicted wound no litigation win can reverse.