Towards the start of the American Revolutionary War, Benson approved the course of the Sons of Liberty and gave up, in a measure, his professional prospects then brightly opening and devoted himself to his country: these exertions showed the man's value of this step to both his native state and the cause he aided. He aided the Sons of Liberty, who were in Dutchess County where Benson, as a part of his first efforts, gave proper directions to the political meetings. When the British occupied New York City in 1776, Benson remained in Dutchess County for several years. From 1777 to 1781, Benson served as a member of the New York State Assembly and drafted every important bill passed there in during the Revolution. He was also a representative in the Second Continental Congress from 1780, and drew bills organizing the executive department of the United States. The county made him the president of their committee of safety and in 1777 sent him to the revolutionary New York State Assembly. When the first state government was organized, Benson was appointed the first New York attorney general and served until 1788. He was elected to the Assembly annually until 1781 and again in 1788.