It's also pretty similar to the Defensive Patent License. With that, to receive a free patent license, you have to join the 'community' by licensing all of you

It's also pretty similar to the Defensive Patent License. With that, to receive a free patent license, you have to join the 'community' by licensing all of your patents under the DPL to other community members. If you sue a member anyway, your license is terminated. The language in the DPL is more precise in limiting itself to actual lawsuits (rather than just "claims") and excluding counterclaims, but it's the same general idea. edit: corrected; DPL is not Twitter's license. Twitter's is the "Innovator's Patent Agreement", which is even more broad in its definition of "defensive" lawsuits: (a) against an Entity that has filed, maintained, threatened, or voluntarily participated in a patent infringement lawsuit against Assignee or any of Assignee’s users, affiliates, customers, suppliers, or distributors; (b) against an Entity that has filed, maintained, or voluntarily participated in a patent infringement lawsuit against another in the past ten years, so long as the Entity has not instituted the patent infringement lawsuit defensively in response to a patent litigation threat against the Entity; or (c) otherwise to deter a patent litigation threat against Assignee or Assignee’s users, affiliates, customers, suppliers, or distributors.