Cahill was hailed at the time of his appointment as SFPD chief by Mayor George Christopher. Cahill, in an interview with local San Francisco media shortly before his death, claimed his relationship with Mayor John F. Shelley was broken by the Summer of Love in 1967: "Jack Shelley, (a Democrat, former liberal congressman and labor leader), did not want to show a heavy hand toward the Hippie & Flower Children element." When hippies flooded Golden Gate Park and the Haight-Ashbury district, Cahill contacted the new California governor, Ronald Reagan, for the California Highway Patrol and the California National Guard to enter San Francisco and sweep the hippies from the city. By law, Reagan needed a request from Shelley. Reagan and Cahill pleaded for his signature, Shelley refused.