Domestic Spying

JB

Months after the Sept. 11 attacks, President Bush secretly authorized the National Security Agency to eavesdrop on Americans and others inside the United States to search for evidence of terrorist activity without the court-approved warrants ordinarily required for domestic spying, according to government officials.

Under a presidential order signed in 2002, the intelligence agency has monitored the international telephone calls and international e-mail messages of hundreds, perhaps thousands, of people inside the United States without warrants over the past three years in an effort to track possible "dirty numbers" linked to Al Qaeda, the officials said. The agency, they said, still seeks warrants to monitor entirely domestic communications.

The previously undisclosed decision to permit some eavesdropping inside the country without court approval was a major shift in American intelligence-gathering practices, particularly for the National Security Agency, whose mission is to spy on communications abroad. As a result, some officials familiar with the continuing operation have questioned whether the surveillance has stretched, if not crossed, constitutional limits on legal searches.

"This is really a sea change," said a former senior official who specializes in national security law. "It's almost a mainstay of this country that the N.S.A. only does foreign searches."

The legal opinions that support the N.S.A. operation remain classified, but they appear to have followed private discussions among senior administration lawyers and other officials about the need to pursue aggressive strategies that once may have been seen as crossing a legal line, according to senior officials who participated in the discussions.

For example, just days after the Sept. 11, 2001, attacks on New York and the Pentagon, Mr. Yoo, the Justice Department lawyer, wrote an internal memorandum that argued that the government might use "electronic surveillance techniques and equipment that are more powerful and sophisticated than those available to law enforcement agencies in order to intercept telephonic communications and observe the movement of persons but without obtaining warrants for such uses."

Mr. Yoo noted that while such actions could raise constitutional issues, in the face of devastating terrorist attacks "the government may be justified in taking measures which in less troubled conditions could be seen as infringements of individual liberties."

The next year, Justice Department lawyers disclosed their thinking on the issue of warrantless wiretaps in national security cases in a little-noticed brief in an unrelated court case. In that 2002 brief, the government said that "the Constitution vests in the President inherent authority to conduct warrantless intelligence surveillance (electronic or otherwise) of foreign powers or their agents, and Congress cannot by statute extinguish that constitutional authority."

Administration officials were also encouraged by a November 2002 appeals court decision in an unrelated matter. The decision by the Foreign Intelligence Surveillance Court of Review, which sided with the administration in dismantling a bureaucratic "wall" limiting cooperation between prosecutors and intelligence officers, cited "the president's inherent constitutional authority to conduct warrantless foreign intelligence surveillance."

But the same court suggested that national security interests should not be grounds "to jettison the Fourth Amendment requirements" protecting the rights of Americans against undue searches. The dividing line, the court acknowledged, "is a very difficult one to administer."