As Tim Lynch and I detail in our new study Power Surge: The Constitutional Record of George W. Bush, the Bush administration has advanced an extraordinarily broad theory of presidential power during the war on terrorism. The claim that shows up again and again—in the torture memos, in the enemy combatant cases, in the wiretapping controversy—is that the president’s “inherent executive authority” and powers as commander in chief allow him to override validly enacted statutes that proscribe tactics he wants to pursue in the war on terror.

But surely there are limits to this theory, boundaries that even a wartime president cannot cross, right? Well, if there are, administration officials have been pretty cagey about identifying them. At a Senate Judiciary Committee hearing in February, Attorney General Alberto Gonzales stonewalled like a Supreme Court nominee when asked about limits to the president’s power. To questions like “Can the president suspend the application of the Posse Comitatus Act legally?” he’d offer only, “Those are very, very difficult questions. And for me to answer those questions, sort of, off the cuff, I think would not be responsible.”

In April, before the House Judiciary Committee, Gonzales suggested that the president has inherent authority to wiretap Americans’ domestic communications–calls and emails where both parties are in the United States–without a warrant. That day, the Justice Department issued a “nonclarification clarification” of the AG’s remarks: “The attorney general’s comments today should not be interpreted to suggest the existence or nonexistence of a domestic program or whether any such program would be lawful under the existing legal analysis.” Anyone looking for a straight answer on limits to “inherent executive authority” would be well-advised to look elsewhere.

A few months back, CBS’s Bob Schieffer decided to ask the president himself: “Do you believe that there is anything that a president cannot do, if he considers it necessary, in an emergency like this?” Here’s the president’s response:

PRESIDENT BUSH: That’s a–that’s a great question. You know, one of the–yeah, I don’t think a president can tort–get–can order torture, for example. I don’t think a president can order the assassination of a leader of another country with which we’re not at war. Yes, there are clear red lines, and–it–you–you–you just asked a very interesting constitutional question. The extent to which a president, during war, can exercise authorities in order to protect the American people, and that’s really what the debate is about.

It’s a very interesting answer, because, as Jacob Sullum pointed out recently, neither example represents a case in which the president considers himself bound by law or by anything other than his own sense of self-restraint. Assassination is barred by an executive order that the president himself could change. As for torture, the administration has never repudiated the theory of uncheckable executive power outlined in the Justice Department’s torture memos. And recently, when President Bush signed the McCain Amendment reaffirming the ban on torture, the president suggested in the signing statement that he could interpret it out of existence if he thought it necessary.

Given all that, Schieffer’s question still stands: in the administration’s constitutional theory, is there anything that a president cannot do, if he considers it necessary? It would be good–or at least clarifying–to have an answer, even if that answer turns out to be “no.”