(Bloomberg) -- Former President George W. Bush’s administration told a secret court that it was justified in intruding into personal privacy by intercepting e-mails and other communications without warrants to prevent terror attacks.

The government argued the communications would give authorities an early warning about terrorists’ plans, according to a 2006 Bush administration legal memo released today in response to a public records request.

The document provides the first public airing of the original legal arguments the administration made to the U.S. Foreign Intelligence Surveillance Court, which oversees warrantless spying.

The government’s “overwhelming interest in detecting and thwarting” possible terrorist attacks “is certainly sufficient to make reasonable the intrusion into privacy involved in targeting collection at communications,” according to the document from then-Attorney General Alberto Gonzales and other top Bush administration officials.

The administration had been conducting the warrantless spying -- known as the terrorist surveillance program -- since the 2001 terrorist attacks on the U.S. without court or congressional authorization. The administration sought approval for the program from the court in response to public and congressional outrage after it was described by the New York Times and other news organizations.

‘Compelling Interest’

“The government’s interest in conducting the surveillance is the most compelling interest possible -- securing the nation from foreign attack in the midst of an armed conflict,” according to the partially redacted document released by the Office of Director of National Intelligence.

The DNI released five additional documents today, including a court order dated Jan. 10, 2007, approving the government’s request. The order came with a few conditions, including a required review by officials from the Justice Department and National Security Agency to ensure the surveillance was conducted legally.

The spying effort eventually became known as the Prism program, under which the U.S. compels Internet companies to turn over e-mails and other electronic communications. Prism and other spy programs were exposed by former government contractor Edward Snowden, beginning in June 2013.

The Bush administration requested, and received, approval to intercept communications of suspected foreign terrorists inside the U.S. without warrants, even if one end of the communications involved a U.S. citizen.

Internet Traffic

“A vast proportion of the world’s Internet traffic is carried at some point on the communications infrastructure in the United States,” Gonzales and the others wrote. U.S. enemies “seek to use our own communications infrastructure and laws against us, as they secrete agents into the United States, waiting to attack at a time of their choosing.”

According to the document, the program was designed “to alert the U.S. government to the presence of members and agents of these foreign powers and to aid in tracking such individuals within the United States.”

Gonzales and the others argued that specific warrants weren’t needed.

“Collecting foreign intelligence in time of armed conflict is far removed from the ordinary criminal law enforcement action to which the warrant requirement is particularly suited,” they wrote.

Legal Argument

They also argued the authority being sought didn’t violate the Fourth Amendment, which prohibits the government from doing unreasonable searches and seizures without specific warrants.

Some lawmakers and privacy advocates have said U.S. spying programs have overreached, leading to a chill on free speech and violating privacy rights of U.S. citizens. The document also sought to counter that argument.

“The government would be engaged in a legitimate investigation whose aim is to prevent international terrorism, not to suppress speech or to harass dissident organizations,” it said.

“The only way for the government to locate terrorist operatives is if they continue to communicate with each other using means which they believe -- incorrectly -- are free from the risk of detection.”