In a unanimous ruling, the court said that "hard-sell tactics directed at middle school students could lead to exploitation, distort competition between high school teams and foster an environment in which athletics are prized more highly than academics."

Games have rules, Justice John Paul Stevens said for the court. "It is only fair that Brentwood follow them," Stevens said.

Brentwood argued that the restriction violated its free-speech rights, even though it voluntarily joined the association.

The dispute arose from a letter that Brentwood's football coach sent to a dozen eighth-graders in 1997, inviting them to attend spring training at Brentwood. The students already had been accepted and signed enrollment contracts for the fall.