Timeline of revelations about U.S. domestic spying

U.S. President Barack Obama leaves after speaking in San Jose, Calif. , Friday, June 7, 2013. (AP / Evan Vucci)

President Barack Obama is defending secret government programs that sweep up Internet data and millions of Americans' phone records in their search for foreign terrorists.

A timeline of controversies surrounding spy programs and privacy:

1978: In response to outrage over spying on activists and other U.S. citizens, Congress passes the Foreign Intelligence Surveillance Act. It creates a secret court to monitor spying within the United States. Known as the FISA court, its judges sign off on wiretapping and search warrants used against foreign agents and suspected spies and terrorists and Americans involved with them.

September 2001: The shock of the Sept. 11 attacks on New York and Washington pushes George W. Bush's administration to seek new powers to improve intelligence-gathering and prevent terrorism.

October 2001: Congress and Bush rush the USA Patriot Act into law. It gives the government unprecedented authority to search, seize, detain or eavesdrop in pursuit of suspected terrorists. Because of privacy concerns, lawmakers make the eavesdropping provisions and other controversial aspects temporary, requiring renewal by Congress.

December 2005: The New York Times reports that the National Security Agency is secretly eavesdropping on telephone calls and emails of Americans communicating with people outside the United States, without seeking warrants from the FISA court. What becomes known as "warrantless wiretapping" began in 2002 under a presidential order. Critics call it unconstitutional, but the Bush administration says it's legal.

March 2006: Congress votes to renew the Patriot Act, although lawmakers voice concerns about the government's broad powers to conduct surveillance and collect data.

May 11, 2006: USA Today reports that the NSA is secretly collecting phone records of millions of Americans in a giant database. Some of the phone companies cited dispute the story.

August 2006: A federal judge in Detroit rules that the NSA's warrantless surveillance program is unconstitutional because it infringes on free speech, privacy and the separation of powers. The program continues as the case is appealed.

January 2007: Responding to the court challenge and lawmakers' concerns, Bush suddenly changes course. His administration announces it will begin seeking approval from the FISA court when eavesdropping on telephone calls between the U.S. and other countries in pursuit of terrorists.

August 2007: Congress approves changes sought by the Bush administration to the FISA Act, officially allowing NSA eavesdropping on communications between an American and a suspect foreigner, without a FISA judge's approval.

May 2011: Congress passes and Obama signs a four-year extension of Patriot Act provisions on record searches and roving wiretaps. Some lawmakers complain that the law doesn't do enough to protect Americans' privacy and the disagreement forces the renewal to the last minute.

June 5, 2013: A British newspaper, The Guardian, reports that the NSA is collecting the telephone records of millions of American customers of Verizon under a top secret court order. Security experts say the records of other phone companies are also involved.

June 6, 2013: The Guardian and The Washington Post report that the NSA and the FBI are tapping into U.S. Internet companies, including Google and Facebook, scooping out emails, photos and videos to track foreign nationals who are suspected of terrorism or espionage. That night, in a rare disclosure, Director of National Intelligence James Clapper reveals some information about the programs to counter what he says is the "misleading impression" created by news coverage. Clapper says the government is prohibited from "indiscriminately sifting" through the data and can only review it when the query involves a reasonable suspicion that a foreign terrorist organization is involved. Clapper says articles about the Internet program "contain numerous inaccuracies" but does not specify what those might be.

June 7, 2013: Obama defends the programs, saying he came into office with "healthy skepticism" about them and has increased some safeguards to protect privacy. But he offers assurances that "nobody is listening to your telephone calls" or reading citizens' emails. Obama says privacy must be balanced with security: "We're going to have to make some choices as a society."

June 8, 2013: For the second time in three days, Clapper takes the unusual step of declassifying some details of an intelligence program in response to media reports. He says the government program for tapping into Internet usage is authorized by Congress, falls under strict supervision of a secret court and cannot intentionally target a U.S. citizen. Clapper says the data collection had the approval of the secret Foreign Intelligence Surveillance Act Court and was done with the knowledge of Internet service providers. He says media revelations of government intelligence-gathering programs are reckless and give America's enemies a "playbook" on how to avoid detection.