In 1909, running on the Republican-Fusion Ticket, Max was elected New York County Register. He made many changes in the property registration methods of the office. In 1913, again running as a Republican-Fusion candidate, he was elected Sheriff. During his term, Harry Thaw and police lieutenant Charles Becker were among his prisoners. Harry Thaw was the murderer of the renowned architect Stanford White. Charles Becker was the first American police officer to ever receive the death penalty. The scandal that surrounded his arrest, conviction, and execution was one of the most important in Progressive Era New York City. While serving as Sheriff, Max urged that a law be passed providing for payment of Sheriff's fees into the public treasury instead of to the Sheriff. He held that the Sheriff's remuneration was excessive. He was the first Sheriff of New York County to reveal what the fees and salary amounted to, saying that he received $113k for his first two years in office ($113k in 1915 = $2.72 mil in 2017). In May 1916, a few months after Max retired from office, Governor Whitman signed a bill abolishing payment of fees to Sheriffs, to take effect "after" the term of Alfred E. Smith, Max's successor. Max was key in bringing an end to the corruptible practice of paying fees directly to the Sheriff. Because of his poverty-stricken childhood, Max was always passionate about helping the poor. This was apparent throughout his political life; he pushed to establish medical clinics, parks, and playgrounds on the East Side of New York. He was also a liberal contributor to charity. Max was very active in the affairs of the Hebrew Orphan Asylum and gave considerable sums toward its upkeep. Max was a trustee for the last twenty five years of his life and was the third oldest member of the board at his death. He was also the second oldest member of the congregation of Temple Israel of the City of New York. In 1918, Max was urged to run for Congress, but declined. He took an active interest in Republican affairs until his death, however, often making campaign speeches. He belonged to the National Republican Club and the Riverside Republican Club, and was a founder of the New York County Republican Club. In 1913, Max Grifenhagen purchased "Stonehurst", a house in Freeport, as a summer residence. Stonehurst is the name of the house located at 314 South Ocean Avenue. Built by Benjamin Homan around 1901, this shingle-style home includes field stone accents, a magnificent chimney, and several outer buildings.