Having already been involved in a contract dispute with the Patriots, Kapp refused to sign a standard players contract for the 1971 season and quit the team in July, then filed an antitrust suit against the N.F.L. A jury declined to award him damages, but the case represented an early challenge in the players’ ultimately successful struggle to win free agency rights.

Joseph Robert Kapp was born on March 19, 1938, in Santa Fe, N.M., the oldest of five children of Florence Garcia Kapp, who was of Mexican heritage, and Robert Kapp, a salesman, who was of German descent.

His family moved to California when Joe was young. He played football and basketball in high school and received an athletic scholarship from the University of California, Berkeley.

Kapp led the Golden Bears to the Pacific Coast Conference football championship in 1958 and a berth in the Rose Bowl game, a loss to Iowa. He played basketball for the Cal teams that won a pair of Pacific Coast championships.

A bruising 6 feet 2 inches and 205 pounds, Kapp set a career rushing record for Cal quarterbacks, running for 931 yards in three seasons. But the Golden Bears employed a split-T formation favoring quarterback-option running plays over the passing game, so Kapp wasn’t selected in the 1959 N.F.L. draft until the Washington team, now called the Commanders, chose him in the 18th round. They never contacted him, so he went to the Canadian Football League.

Kapp spent a season and a half with the Calgary Stampeders, then was traded to the British Columbia Lions after undergoing knee surgery. He led them to the 1963 Grey Cup game for the C.F.L. championship, a loss to the Hamilton Tiger-Cats, but they defeated Hamilton, 34-24, for the 1964 Grey Cup title. He was a two-time C.F.L. All-Star, threw for 136 touchdown passes and was inducted into the Canadian Football Hall of Fame in 1984.