The U.S. has passed a number of new laws and tightened enforcement of others since the attacks of 9–11. These laws are affecting scientific research and higher education in many ways. This Chapter explores the impacts on science in several areas: foreign students and visitors; the use of certain chemical and biological agents in the laboratory; restrictions on federal grants and contracts; publication of research results, and dissemination of “sensitive but unclassified” scientific information. Some of the new laws and policies may turn out to be counterproductive, reducing U.S. security by retarding scientific and technological development.