Last June, two investigators employed by the Department of Homeland Security showed up at David Streever’s house in Rochester, New York. Streever was not home, so they left him a note.That note, presented as an official warning from U.S. Immigration and Customs Enforcement, is at the center of a First Amendment lawsuit that Streever filed last month, alleging that ICE agents investigated and threatened him based on his constitutionally protected criticism of their boss. This month, the government responded to Streever’s lawsuit, confirming his allegations while attempting to rebut them.On Jan. 26, two days after DHS agents fatally shot Minneapolis...