Is it possible that espionage could be restricted by international agreement? Remarkably, the answer is yes. The proof of principle lies in the fact that the United States and its allies Canada, Australia and the United Kingdom have committed not to engage in espionage against one another. Now that international relations are being roiled by intelligence activities such as the alleged espionage by FBI agent Robert Hanssen and the contested U.S. surveillance flights off the coast of China, some are starting to ask whether the time has come to establish new rules of the road for intelligence collection.