Messenger has litigated nearly 100 cases including over a dozen at the Appellate-level on behalf of Foundation-aided employees and other individuals. His cases defend workers’ freedom from compulsory unionism and focus on the First Amendment and other constitutional rights. He has argued twice before the U.S. Supreme Court. Messenger successfully argued Harris v. Quinn in 2014, securing a Supreme Court ruling that requiring homecare providers to pay union fees violated the First Amendment.