The Cold War is probably the closest historical lab experiment about espionage. I've seen it argued that even the spies and traitors served a valuable purpose

The Cold War is probably the closest historical lab experiment about espionage. I've seen it argued that even the spies and traitors served a valuable purpose during the Cold War. Because leaks like these provided a way for valuable information to cross the barriers of antagonism and give insight into the real problems and the real fears of the other side. And this knowledge could in fact lower tensions and increase security. To know and to tell secrets is a very human thing that laws and social norms (spying on the President! For shame!) will not erase.