Also in 1729, De Lancey was made a member of the New York Assembly, and in 1731 was appointed as second justice of the Supreme Court of New York. In 1730, De Lancey was chosen to lead a commission to frame a new charter for the City of New York. Passed into law in 1732 by the New York Assembly, "the Montgomerie Charter," was principally the work of James De Lancey, who, for his services, was presented with the Freedom of the City Medal. In 1733, on the removal of chief justice Lewis Morris, De Lancey was appointed in his stead, and served as chief justice of New York for the remainder of his life. He presided over the 1735 trial of journalist John Peter Zenger on charges of sedition and libel against Governor William Cosby. Zenger won his case, and the Zenger trial is recognized as a landmark case in establishing freedom of the pressin America. In 1744, one year into George Clinton's position as Governor of New York, De Lancey was granted a commission as New York's chief justice where he became a dominant political force with many relying on his support for their continued time in office and salary. In the same year, he was elected a member of The American Philosophical Society. In 1746 a dispute arose between Governor George Clinton and the New York Assembly regarding the governor's salary. Chief Justice De Lancey supported the legislature's position in the controversy, thus incurring the enmity of Governor Clinton, who subsequently refused to acknowledge a commission from King George II, appointing De Lancey as Lieutenant Governor of New York. Governor Clinton withheld De Lancey's commission as lieutenant governor until October 1753. With the advent of the French and Indian War, Lt. Gov. De Lancey convened and presided over a congress of colonial delegates held in Albany, New York in June 1754, for the purpose of establishing an alliance with the Indians for the common defense against the French. In October 1754, Lt. Gov. De Lancey granted a charter for the creation of King's College. In July 1755, Lt. Gov. De Lancey attended a council of governors of the colonies, held at Alexandria, Virginia, to coordinate defense matters with General Braddock against the French. In September 1755, Sir Charles Hardy arrived from London and assumed the functions of Governor of New York, thus returning Lt. Gov. De Lancey to his role as Chief Justice. Hardy's tenure as governor came to an end in July 1757, when Sir Charles took command of a military expedition to Louisbourg, Nova Scotia, once again leaving De Lancey the de facto ruler of the province, which he remained till his death.
