After the war ended, although principally an associate justice of the state Supreme Court, Yates maintained a modest legal practice and continued surveying as well. During the 1780s, his political star continued to rise in the "party" of Governor George Clinton as he spoke in opposition to the expansion of the scope of a national government. In 1787, he was appointed with John Lansing Jr. and Alexander Hamilton to represent New York at the Philadelphia Convention to revise the Articles of Confederation. Arriving in Philadelphia, Yates and Lansing felt the mood of the convention to produce an entirely new form of government was beyond their authority. After sending a letter to Governor Clinton urging opposition to the new Constitution, they returned home. Yates's personal notes from the Philadelphia convention were published in 1821.