 He helped draft and secure the passage of the National Defense Act of 1916, the Selective Service Act of 1917, and the National Defense Act of 1920.He served as chairman of Committee on Military Affairs (66th–68th Congresses).Representative Kahn also authored the Kahn Exclusion Act, ultimately enacted as the Alien Exclusion Act, telling Congress that "I submit if the Chinese people themselves would deal honestly with us, and if they resorted less to trickery and duplicity to circumvent our laws, then there would be no need of closing up all possible loopholes in the law with the seemingly severely restrictive measures that the Chinese themselves make necessary."