Ainey was a delegate to the International Parliamentary Union for International Peace held at Geneva, Switzerland, in 1912, and at The Hague in 1913. He served as secretary and president of the Japanese-American group of inter-parliamentarians and delegate in 1914 to Tokyo, Japan, and to Stockholm, Sweden. He resumed the practice of law in Montrose.
Ainey was an active participant in international diplomacy, serving as a delegate to various peace conferences and holding leadership positions within the Japanese-American inter-parliamentarian group. After engaging in this work, he returned to practicing law in Montrose.