The latest “imperial presidency” controversy in Washington involves President Bush’s statement, in conjunction with signing a postal reform bill, claiming what the New York Daily News breathlessly calls “sweeping new powers to open Americans’ mail without a judge’s warrant.”

As usual, this turns out to be a tempest in a teapot — notwithstanding the tut-tutting from Senators Susan Collins, Chuck Schumer and Hillary Clinton, as well as NYC Mayor Michael Bloomberg.

To reiterate, the Fourth Amendment prohibits unreasonable searches, not warrantless searches. Consequently, the courts have recognized for years that exigent circumstances justify agents in conducting a search without a judicial warrant.

Furthermore, the president has inherent authority under Article II of the constitution to conduct warrantless searches for national security purposes — at least when the nation is threatened by a foreign power. Thus, for example, did Clinton administration Deputy Attorney General Jamie Gorelick quite correctly insist, in 1994 testimony before Congress, that the president maintained the power to conduct warrantless national security searches even though Congress was then expanding FISA (the Foreign Intelligence Surveillance Act which governs national security wiretaps) to cover physical searches.

There is, as White House spokesman Tony Snow explained, absolutely nothing new about this.

From a political standpoint, it’s certainly worth asking why the White House thought it would be a good idea for the president to issue a signing statement claiming the power to open mail without a warrant in exigent circumstances. After all, if he has the power he has it, whether he talks about it in a signing statement or not — so all the signing statement has accomplished is a few days of media attacks and maybe some subpoenas from and indignant hearings by the Democratic congress in the coming weeks. But this is, or at least it should be, much ado about nothing.