From Schneier on Security
Illegal wiretapping of Americans is nothing new. In the 1950s and ’60s, in a program called "Project Shamrock," the NSA intercepted every single telegram coming into or going out of the United States. It conducted eavesdropping without a warrant on behalf of the CIA and other agencies. Much of this became public during the 1975 Church Committee hearings and resulted in the now famous Foreign Intelligence Surveillance Act (FISA) of 1978.
The NSA’s ability to eavesdrop on communications is exemplified by a technological capability called Echelon. Echelon is the world’s largest information "vacuum cleaner," sucking up a staggering amount of voice, fax, and data communications — satellite, microwave, fiber-optic, cellular and everything else — from all over the world: an estimated 3 billion communications per day. These communications are then processed through sophisticated data-mining technologies, which look for simple phrases like "assassinate the president" as well as more complicated communications patterns.
The fundamental issue here is security, but it’s not the security most people think of. James Madison famously said: "If men were angels, no government would be necessary. If angels were to govern men, neither external nor internal controls on government would be necessary." Terrorism is a serious risk to our nation, but an even greater threat is the centralization of American political power in the hands of any single branch of the government.
"Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves." — William Pitt, House of Commons, 11/18/1783.