"President Bush has quietly claimed sweeping new powers to open Americans' mail without a judge's warrant."

So the Daily News wrote back in January:

Experts said the new powers could be easily abused and used to vacuum up large amounts of mail.

"The [Bush] signing statement claims authority to open domestic mail without a warrant, and that would be new and quite alarming," said Kate Martin, director of the Center for National Security Studies in Washington.

"The danger is they're reading Americans' mail," she said.

"You have to be concerned," agreed a career senior U.S. official who reviewed the legal underpinnings of Bush's claim. "It takes Executive Branch authority beyond anything we've ever known."

A top Senate Intelligence Committee aide promised, "It's something we're going to look into."

Most of the Postal Accountability and Enhancement Act deals with mundane reform measures. But it also explicitly reinforced protections of first-class mail from searches without a court's approval.

What's really going on here? My colleague Anuj Desai has a spiffy little article explaining the law, where a lot hangs on the way the words "letter" and "mail" don't mean the same thing:

I conclude that the statutory prohibition on mail opening only applies to mail matter that falls into the category of “letter” - which, roughly speaking, is defined as a “message” or “communication” or “correspondence.” The prohibition on mail opening thus does not apply to mail matter other than “correspondence,” such as bombs, anthrax or any ordinary good. The statute bars the opening of letters without a warrant, subject to only one relevant exception: the “physical searches” provisions in the Foreign Intelligence Surveillance Act (“FISA”). The government may not open letters without either a warrant or following the procedures set forth in FISA. There is no “exigent circumstances” exception for letters, though the government may temporarily detain a letter for the purpose of obtaining a warrant.

On the other hand, the government may open other mail matter without a warrant subject only to the strictures of the Fourth Amendment. The Fourth Amendment does contain an “exigent circumstances” exception to the ordinary rule that a warrant is required. Thus, scenarios that might involve hazardous materials such as anthrax or a ticking time bomb would in many circumstances fall into this exception.

You can download the paper here.