In early 1969, soon after the Soviet invasion of Czechoslovakia, Tauc left the country. After spending a few months at the University of Paris he moved with his family to Bell Labs in Murray Hill, New Jersey, United States, for a 12-month fellowship. He remained a long-term consultant for Bell Labs after that. In October 1969, when the Czech Academy of Sciences annulled his sabbatical leave and requested his return, Tauc refused and accepted a position of professor of engineering and physics at the Brown University, Rhode Island, which he held until his retirement in 1992. Because of this decision he received a jail sentence in Czechoslovakia that prevented him from visiting the country for decades into the future. At Brown University, he co-authored a patent for a method of characterizing thin films using transient photomodulation spectroscopy. He also wrote several books, served as an editor of three journals, and was a member of the United States National Academy of Sciences. His awards included the 1982 Frank Isakson Prize and the 1988 David Adler Lectureship Award of the American Physical Society. In 2003, long after the fall of the Communist regime, he received the "De Scientia et Humanitate Optime Meritis" medal, the highest award for a scientist in Czech Republic.