What exactly does "If You […] litigation is filed" from Apache2 license mean?

Question

I am not an native English speaker so the paragraph below is really hard for me to understand.

From https://www.apache.org/licenses/LICENSE-2.0:

If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.

Does it mean that if I find a code repository A with Apache2 license and find out that some of code infringe my patents (which means using them without my authorization), and I want to sue the code contributors (e.g. ask them to delete that part of code from A), then I can't use the code A anymore (including building anything based on A)?

Answer 1

Your understanding is close to correct. The rights retracted are limited to patent rights, not rights to use/modify/distribute the software in general.

When an author licenses their work under the Apache 2 license, they offer copyright rights to modify and distribute the software, but also offer rights to any patents they hold that are involved in processes the software performs.

In plain terms, the licensor is saying,

If you're a patent holder and you sue me (or anyone) for infinging your patent in this Apache-licensed software, then you automatically lose the right to use any of my patents granted in this Apache 2 license grant

Practically, that means you couldn't distribute the software (since you'd run afoul of the author's patents that are no longer licensed to you) unless you modified the software to no longer perform processes covered by those patents.

Answer 2

With respect to apsillers, I don't agree with his/her answer as it originally appeared. There are licences where the licence itself terminates on infringement, such as GPLv3 (see s8), but the Apache licence doesn't appear to be one such.

Apache2 s3, which is what you quote above, refers to the grant of patents that accompanies the licence, and deals with the termination of that. Specifically, when someone makes software S available under Apache2 they are covenanting a licence to any of their patents that S might infringe upon, though this licence only covers the context of the software. In other words, A agrees not to give you software S under Apache2 that embodies their patent P, then turn around and sue you for infringing P when you use S.

The clause you quote says that if you decide that S infringes your patent P2 and you decide to sue A for distributing software that embodies P2, your licence to use P (not S) terminates ("then any patent licenses granted to You ... shall terminate").

This will also mean that you can no longer lawfully use S, which looks like a termination of the whole licence. But it's subtly different: if you were to modify S so that it no longer embodies P, you still have the right to use that modified version (say, S2). You may also distribute that version, though if you were to do so under Apache2 you would be convenanting not to sue people who used S2 for violating P2 (assuming S2 embodied P2). If the original licence had terminated in its entirety, you would no longer have the right either to modify S or to distribute S2.