黨外運動
Because of Tsay's support for the Tangwai movement, Taiwan's Kuomintang government blacklisted him, making it impossible for him to return. Instead, he pursued his academic career in the United States for the next eight years, and was naturalised as a U.S. citizen. After conducting postdoctoral research at Cornell University from 1982 to 1983, he took up a position as an assistant professor at Syracuse University, and was promoted to associate professor in 1986. He returned to Taiwan in 1990, a few years after the end of martial law on the island, to take up a new position as a professor at National Taiwan University.