He was one of the senior professors whom the University of California sought to dismiss in the McCarthy era of the early 1950s, because he refused to sign a loyalty oath — not because of any lack of felt loyalty to the United States but because it infringed on academic freedom. Tolman was a leader of the resistance to the oath, and when the Regents of the University of California sought to fire him, he sued. Tolman made an address to the Special Convocation at McGill University on June 11, 1954. In his address he advocated and made argument for the need of academic freedom, as well as criticized scapegoating. The resulting court case, Tolman v. Underhill, led in 1955 to the California Supreme Court overturning the oath and forcing the reinstatement of all those who had refused to sign it.