> 3.4 Patent Claims. If you bring or threaten to bring a patent claim against any Licensor (including any claim, cross-claim or counterclaim in a lawsuit) to enforce any patents that you allege are infringed by any Work, then your rights under this License from such Licensor (including the grant in Section 2.1) will terminate immediately.
Is such a clause legal? I have basically zero knowledge of such things, but it seems like it should be illegal to punish someone for a good faith patent claim.