If you think the government is watching your every move, that's crazy--but if you think the government is too good or too honest to try it, that's naive. Whether in the name of fighting crime, communism, terrorism, anarchy, military enemies, or just in the name of patriotism, our government has watched us before and will watch us again. As technology improves, privacy as we know it will inevitably evaporate; the best we can hope for is the power to watch the watchers.
The Fourth Amendment to the U.S. Constitution explicitly protects "[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures." The U.S. Supreme Court has consistently found that surveillance is comparable to a search and that it therefore ordinarily requires the subject's consent or a valid warrant. Unfortunately, our executive branch doesn't always pay attention to what the U.S. Supreme Court says.
The Right to Privacy
In the past five decades, the U.S. Supreme Court has also determined that the Constitution's Fourteenth Amendment protects a personal right to privacy that is even broader than that which is guaranteed by the Fourth Amendment. Could this concept of a right to privacy potentially be used to exclude government surveillance programs that might also pass constitutional muster? It isn't clear, and in any case the right to privacy is unlikely to be expanded any further by the current Supreme Court than it already is.
In December 2005, the New York Times revealed that the Bush administration had been conducting secret surveillance of international telephone calls by way of the National Security Agency, in violation of the Federal Intelligence Surveillance Act of 1978. The ACLU has challenged this policy in federal court.
Project Echelon (1947-Present)
For six decades, the global Project Echelon has been used to surveil an unknown amount of material with an unknown degree of specificity. While defenders of the project claim that its technology is only used in legal ways, some charge that it is easily abused--and a few have even argued that Echelon has been used to illegally assist with strategy in international business deals.
The Total Information Awareness Program (2002-2003)
The Defense Advanced Research Projects Area (DARPA) of the U.S. Department of Defense set up the Total Information Awareness program in 2002, which promised to provide "total information awareness" through "large, distributed repositories" including "biometric signatures of humans" and "human network analysis and behavior modeling." Congress defunded the program in 2003.
The "Patriot Act II" (never implemented)
In 2003, the draft of a proposed "Patriot Act II"--which would, among other things, allow the government to secretly and permanently "vanish" anyone without trial, including U.S. citizens, if they were suspected of terrorism--was released to the press. Some of the less frightening aspects of the proposed act were later incorporated into the ultimately unsuccessful VICTORY Act proposal.
In 1956, the FBI established its COINTELPRO program to infiltrate, surveil, and work to destroy Communist groups and others deemed threats by the political establishment, which eventually included both extremist groups like the Ku Klux Klan and civil rights groups such as the Student Nonviolent Coordinating Committee (SNCC). It was abolished (or, depending on who you ask, merely renamed) in 1971.