James Risen and Eric Lichtblau break a tremendously important story in tomorrow's New York Times about a secret program that has permitted the NSA to spy without a warrant inside the United States. The story begins:

  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.

  How much monitoring is occurring? Here's what the article says:

  While many details about the program remain secret, officials familiar with it say the N.S.A. eavesdrops without warrants on up to 500 people in the United States at any given time.

  Is this legal, you're wondering? The article offers this:

  Mr. Bush's executive order allowing some warrantless eavesdropping on those inside the United States - including American citizens, permanent legal residents, tourists and other foreigners - is based on classified legal opinions that assert that the president has broad powers to order such searches, derived in part from the September 2001 Congressional resolution authorizing him to wage war on Al Qaeda and other terrorist groups, according to the officials familiar with the N.S.A. operation.
  . . .
  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.

  According to the story, some officials objected, and DOJ audited the program:

  Some agency officials wanted nothing to do with the program, apparently fearful of participating in an illegal operation, a former senior Bush administration official said. Before the 2004 election, the official said, some N.S.A. personnel worried that the program might come under scrutiny by Congressional or criminal investigators if Senator John Kerry, the Democratic nominee, was elected president.

  I hope we'll be hearing more about this in coming weeks, as this is big news. While the statutory privacy laws have an exception for this type of monitoring, see 18 U.S.C. 2511(f), and the constitutional limits on e-mail surveillance are uncertain even in traditional criminal cases, the constitutionality of warrantless interception of telephone calls in situations like this is really murky stuff. To get up to speed on some of the issues, check out Judge Sand's opinion in United States v. bin Laden, 126 F.Supp.2d 264 (S.D.N.Y. 2000). (.pdf)