In the last few days, there has been a lot of press on the Bush Administration's claims that the government can open postal mail without a warrant in some cases. Last Friday's story in the Washington Post is typical:

  President Bush signed a little-noticed statement last month asserting the authority to open U.S. mail without judicial warrants in emergencies or foreign intelligence cases, prompting warnings yesterday from Democrats and privacy advocates that the administration is attempting to circumvent legal restrictions on its powers.
  A "signing statement" attached to a postal reform bill on Dec. 20 says the Bush administration "shall construe" a section of that law to allow the opening of sealed mail to protect life, guard against hazardous materials or conduct "physical searches specifically authorized by law for foreign intelligence collection."
  White House and U.S. Postal Service officials said the statement was not intended to expand the powers of the executive branch but merely to clarify existing ones for extreme cases.
  "This is not a change in law, this is not new, it is not . . . a sweeping new power by the president," spokesman Tony Snow told reporters. "It is, in fact, merely a statement of present law and present authorities granted to the president of the United States."
  But some civil liberties and national-security law experts said the statement's language is unduly vague and appears to go beyond long-recognized limits on the ability of the government to open letters and other U.S. mail without approval from a judge.
  Kate Martin, director of the Center for National Security Studies in Washington, said the government has long been able to legally open mail believed to contain a bomb or other imminent threat. But authorities are generally required to seek a warrant from a criminal or special intelligence court in other cases, Martin and other experts said.
  "The administration is playing games about warrants," Martin said. "If they are not claiming new powers, then why did they need to issue a signing statement?"
  Administration critics said they were particularly confused because the relevant portion of the postal reform legislation — which prohibits opening mail without warrants in most circumstances — remains unchanged.

  So there are two accounts of what is happening. In the first account, the Bush Administration is unilaterally asserting new powers to open mail; in the second, the Administration is simply restating long-settled law. But which account is correct? My own answer is that I'm not sure yet. There may be nothing here, but there's a possibility that there is something important.

  Here's what I could figure out. The Postal Accountability and Enhancement Act was passed in late December, and mostly regulates the internal operations of the U.S. Postal Service. It's really dry stuff about employment law, perhaps interesting if you work at the Postal Service (or you're an employment lawyer) but not otherwise.

  The relevant section of the Act is Section 1010(e), which comes at the very end of the act in a section about "technical and conforming amendments." This section doesn't do much: it simply moves a paragraph of statutory text from one place in the U.S. Code to another. Specifically, the section takes a paragraph from 39 U.S.C. 3623(d) — a paragraph that has been there since the 1970s — and moves it to 39 U.S.C. 404(c). Here is the paragraph that has been moved from one section to another:

The Postal Service shall maintain one or more classes of mail for the transmission of letters sealed against inspection. The rate for each such class shall be uniform throughout the United States, its territories, and possessions. One such class shall provide for the most expeditious handling and transportation afforded mail matter by the Postal Service. No letter of such a class of domestic origin shall be opened except under authority of a search warrant authorized by law, or by an officer or employee of the Postal Service for the sole purpose of determining an address at which the letter can be delivered, or pursuant to the authorization of the addressee.

  Okay, so that brings us to the President's signing statement. The signing statement for this Act has the following to say about the technical amendment in Section 1010(e):

The executive branch shall construe subsection 404(c) of title 39, as enacted by subsection 1010(e) of the Act, which provides for opening of an item of a class of mail otherwise sealed against inspection, in a manner consistent, to the maximum extent permissible, with the need to conduct searches in exigent circumstances, such as to protect human life and safety against hazardous materials, and the need for physical searches specifically authorized by law for foreign intelligence collection.

  So what does this signing statement mean? First, it pretty clearly says that the Administration reads the moved paragraph as having implicit exceptions that track the Fourth Amendment's exceptions to the warrant requirement. The Fourth Amendment has long required a search warrant to open postal mail, subject to the usual Fourth Amendment exceptions such as exigent circumstances. The signing statement appears to say that the Administration construes that law as implicitly incorporating the Fourth Amendment's warrant exceptions. In other words, the law isn't intended to require federal officials to obtain a warrant when exigent circumstances or other exceptions exist.

  The second possible meaning of the signing statement is that the Executive may construe other statutory laws as authorizing warrantless searches, and that in those cases the other laws trump. "Physical searches specifically authorized by law for foreign intelligence collection" could refer to searches authorized under the emergency exception to FISA's rules requiring a warrant for physical searches, or might possibly — and here is where it gets interesting — refer to the AUMF.

  Is this something new? Is this construction of the statute the same construction the executive has always taken, or does it reflect a change in policy? In other words, does the issuance of the signing statement for this technical amendment simply signal the Bush Administration's unusual overreliance on signing statements — so much that they would make a statement to restate existing law even when the paragraph is just moved from one place to another — or does it hint at a previously unknown Administration's practice?

  I don't know. My guess is that the signing statement doesn't signal a major reinterpretation of the statute as against Fourth Amendment exceptions. Here, my thoughts are very tentative: I spent about a half hour looking for cases that would answer whether the postal statute block searches in exigent circumstances or when another exception to the warrant requirement applies, and came up mostly empty. Somewhat to my surprise, I could only find a handful of suggestions and snippets on this, none of which was certain. (The reason for the lack of cases may be that exigent circumstances may require the seizure of mail, but won't often require its search. I'm not sure.) On the whole, though, this led me to think that the statute has in the past been understood to be more about internal postal service procedures rather than investigations, so it would make sense for the statute to not trump the usual Fourth Amendment doctrines allowing warrantless exigent circumstances searches.

  But what if the signing statement isn't really about recognizing constitutional exceptions, but rather the Bush Administration's reading of the AUMF? Recall our many discussions about the legality of the NSA domestic surveillance program. FISA's prohibition on physical searches for national security reasons has the same prohibition as FISA's prohibition on wiretapping: it also prohibits searches "except as authorized by statute." 50 U.S.C. 1827(a)(1).

  DOJ's defense of the NSA surveillance program argues that the AUMF is clear statutory authorization to use fundamental tools of war to fight terrorism, and that "[e]lectronic surveillance is a fundamental tool of war that must be included in any natural reading of the AUMF's authorization to use 'all necessary and appropriate force.'" Thus, in the Administration's view, the AUMF is statutory authorization to conduct electronic surveillance. If electronic surveillance is a fundamental tool of war, then presumably postal surveillance is a fundamental tool of war, as well. I can't think of a reason why you would think the AUMF allows national security wiretapping but not national security letter-opening. If you can intercept John's e-mail to Jane for national security reasons, presumably you can intercept John's snail mail to Jane, too.

  So where does that bring us? Not to any certainty, unfortunately. It may be that this signing statement is nothing, and it just reveals the Administration's willingness to issue signing statements about everything. On the other hand, it may be that it hints at a program allowing the government to open postal mail under the claimed authority of the AUMF.