Cullinan entered Cornell University in 1869. He was the first president of the Cornell Baseball Team and was the class orator at his graduation in 1872. He then studied law and practiced in Oswego[2] after he was admitted to the bar in 1875.[3]
While in the Assembly, Cullinan was involved in the struggle to elect new Senators following the resignation of Roscoe Conkling and Thomas C. Platt, with Cullinan supporting both men being returned to the Senate. He was also chairman of the Assembly Committee on General Laws and focused on codifying the state's general laws regarding corporations. In 1893, he was Chairman of the Republican State Convention. In 1896, when the State Excise Department was organized, he was appointed its General Counsel. He prepared the forms and blanks for the department, formulated legal methods to enforce the Liquor Tax Law, and secured a harmonious line of judicial decisions throughout the state. After Commissioner Henry H. Lyman died in 1901, Cullinan was appointed his replacement.[1]
Cullinan served as Excise Commissioner until 1906. He was a delegate-at-large to the 1915 New York State Constitutional Convention.[6] Following his retirement as Excise Commissioner, he formed a law partnership with Udelle Bartlett called Cullinan & Bartlett.[7]