Perry Education Association (PEA) (defendant) was elected as the exclusive bargaining representative for the teachers of the Metropolitan School District of Perry Township, Indiana. A collective-bargaining agreement with the Board of Education provided that only PEA would have access to the interschool mail system and teacher mailboxes in the Perry Township schools. As a result, a different union, Perry Local Educators’ Association (PLEA) (plaintiff), was denied access. PLEA brought suit in federal district court on the grounds that the denial of access violated the First and Fourteenth Amendments. The district court denied relief for PLEA, but the court of appeals reversed. PEA appealed to the United States Supreme Court.