A great letter to gain an understanding of the issues: "... The blocking of users from your Twitter account suppresses speech in a number of ways. Users who have been blocked cannot follow you on Twitter, and they are limited in their ability to view your tweets, find your tweets using Twitter’s search function, and learn which accounts follow you.4 They are also limited in their ability to participate in comment threads associated with your tweets.5 Blocking users from your Twitter account violates the First Amendment...."