The Detroit Federation of Teachers (the union) and the Board of Education (defendants) negotiated a collective-bargaining agreement that included an agency-shop clause. According to the agency-shop clause, all non-union teachers were required to pay the union a fee that was equivalent to membership dues. The membership dues and agency-shop fees were used to sponsor various social events for union members and support the union’s political, economic, and professional programs. A group of non-union teachers (plaintiffs) sued the Board of Education in trial court, claiming that the agency-shop clause was forcing the plaintiffs to support union activities that the plaintiffs would not otherwise support in violation of their right to freedom of association under the First Amendment. The trial court found in favor of the defendants. The plaintiffs appealed. The appellate court reversed and remanded the trial court’s decision. The Supreme Court of Michigan denied review, and the United States Supreme Court granted review under probable jurisdiction.