… Did you know that something really fundamental had changed in the country [after 9/11]?

Yeah, I think I appreciated that very quickly. I was probably one of the relatively small number of people that knew about Al Qaeda prior to 9/11, and my early assumption was that it was an attack by them and by bin Laden. And the scale of the destruction and devastation and loss of life was immediately apparent, and I think I sensed pretty quickly that this was not garden-variety, low-tech terrorism; this was not business as usual. Something fundamental had changed. It took a day or two for a lot of that to crystallize in my mind after the president had made some pronouncements on the subject, after I had read some additional analyses. But 9/11 was a day that I knew on that day would probably stand out in my memory forever.

And the mood in the White House, when you could get back in there and get to work, what did it feel like? Did it feel different?

Absolutely. It felt very different. In the afternoon of Sept. 11, 2001, the White House staff reconvened in some private offices near the White House to provide the president whatever support he needed. And that was a very somber affair. When I first walked into that building, I was informed by Viet Dinh, who was then assistant attorney general in charge of the Office of Legal Policy, that Barbara Olson, a solicitor general's wife and a friend of mine, had been killed in the attack on the Pentagon, which made everything even more personal than it already was.

The other thing to remember is that there was a palpable sense of threat in the city on that afternoon. Nobody knew whether there were going to be further attacks, and I had to show my White House pass just to get into the city from outside. I had taken my family to a safe place and then turned right around after arranging some law library facilities for me and my colleagues at a local law school for that evening in case we couldn't get back into the White House.

And coming back downtown, by the time I got back downtown, it was an absolute ghost town. There were essentially no cars on the street, military was all over the streets, and it was only my White House credentials that essentially allowed me to get into the center of the city, which was a war zone. So the mood was very, very different. Everybody came in on the morning of Sept. 12, 2001, which was the first day that most of us got back into the complex, I think with a real sense of mission and sense of purpose, and at least for my part a sense of great privilege and good fortune of being in a position where I could try to make a difference in dealing with this new threat.

Did you see the president during those first couple of days?

No, I didn't personally. When a national crisis of this kind occurs, a few things happen. First, power is drawn into the center, so the White House and the White House staff become much more involved in directing day-to-day policy in a variety of areas than they otherwise would be. Under normal circumstances, policy would be developed through a slow, deliberate and interagency process with some supervision by appropriate White House staff. But when decisions have to be made quickly, and when action has to be taken fast, the unitary executive, the president, who's vested with commander-in-chief powers under the Constitution, gathers that power into himself and acts through the people who are directly, most directly, his agents and at his right and left hand. So the White House staff becomes much more involved.

But concomitant with that, the president himself becomes much more scarce to the lower levels of the White House staff. That is, the president himself was spending most of his time only with the senior members of his national security team dealing with this. And those of us who otherwise might have seen him or dealt with him under normal circumstances saw much less of him initially. The chief of staff did try to communicate with the rest of the staff. I remember a meeting that was held in Room 450 of the Old Executive Office Building, where Andy Card, in his typically gracious and understated way, essentially told us, among other things, that the circumstances of our service had obviously changed; that he understood that this is not what we had bargained for when we joined the staff, and it wouldn't be held against any of us if we wanted to leave. Nobody took him up on that invitation, obviously.

But this was at a time when people felt genuinely like the White House was under threat, the White House staff was under threat, the nation as a whole was under threat. We were given security precautions by the Secret Service to take in just commuting to and from home to the White House. There were periodic evacuations of the White House complex during those first couple of weeks, enhancing the sense of threat. We were advised early on that the Secret Service was unable to protect those of us who had offices over on the 17th Street side of the building and that plans were under way to evacuate that side of the building and move offices because the threat of a car bomb or a truck bomb over there with the quantity of glass on that side of the building was too great. But still, there were four or five weeks when those of us with offices on that side of the building had to sit in front of our picture windows wondering whether every unmarked white panel truck passing by represented a potential threat.

There was a member of the staff who for most of the first couple of weeks was literally throwing up in her trash can. In retrospect, I think we all understand that there was nothing for us to really worry about, but people were certainly afraid. Mysterious vans show up on the White House complex, sniffing the air for chemical and biological agents. I mean, it was a radically different atmosphere than it had been. And I remember thinking to myself in the first few days after 9/11 that really everything that had gone before in my White House service just seemed like fun and games by comparison.

… People keep saying to us is there was a lot of talk about being "forward-leaning" in the process and thinking. Tell me what that meant.

Well, there were a powerful set of shared assumptions that we had in the wake of 9/11, and one of the most powerful was the assumption that we would never be forgiven if we failed to do something that was within the power of our government lawfully to protect the public from a further attack. We had no idea whether further attacks were planned. Everybody had to assume at that time that further attacks on the scale of 9/11, or perhaps even worse, were planned. And all of us were concerned with ensuring that the president had the full complement of tools and weapons at his disposal that came with his office, that he was properly advised on how they could and should be used, and that as a whole, the United States government, the executive branch of government, was doing everything that it could to protect the public safety and to try to prevent another loss of life on the scale of 9/11.

And that extended not just to the prevention of further terrorist acts, but also to such considerations as preserving the continuity of our government in the event that we were unable to prevent further attacks and various highly classified programs were triggered for the first time since the depths of the Cold War to ensure that a mass-casualty attack on Washington would not prevent our government from functioning properly.

And thinking about the mind-set that we all brought to our tasks, you have to understand that many of us were spending nights on a regular basis in some very, very unusual places -- things out of a James Bond movie, frankly. And that certainly colors how you think about things. If you believe that the central institutions of our government are under such threat that the people who work for the president need to maintain, as was recorded publicly in the press several months later, in essence a shadow staff in a safe location that would be capable of transferring power to a successor president if the current president were killed in an attack, that certainly underscores the seriousness of the threat that you're facing and how much will and power has to be brought to bear to reduce it.

[When does the idea of whether the Geneva Accords apply begin to get thrashed out?]

We began thinking about potential legal and policy issues that would arise from the capture of foreign terrorists very, very soon after 9/11. ... So the following conundrum occurred to all of us, most of whom had no background at all in these issues, which is this: When you capture a suspected Al Qaeda terrorist, what do you do with him? You can't kill him once you have him in custody and he's been captured. That would be a violation of international law. You can't let him go because he's far too dangerous and potentially far too valuable as a source of intelligence. And you can't, in many cases, try him in the ordinary civilian court system. So what do you do with this person?

The good news is that the United States government has people within it who are experts in virtually every aspect of law, and this case was no exception. It turned out that there was hundreds of years of law on this subject, and the answer was provided by the laws of war, or the laws of international armed conflict.

Of course, before you get there, you have to have accepted the paradigm shift, that this is in fact a matter of war and that it calls for the exercise of the president's powers as commander in chief and a military response, rather than a matter of law enforcement that call for an exercise of the president's powers as the nation's chief law enforcement officer. But the president articulated forcefully and very convincingly in the wake of 9/11 that the nation was, in fact, at war with these people. Our adversaries had known that and publicly declared that for a long time, but we had made the mistake of not taking them at their word and not taking them quite seriously enough.

But once you appreciate and understand that this is in fact an existential threat to our government and to our way of life, that it is a military conflict, even if of an unconventional character, the answers to a lot of these questions about how to deal with detainees become fairly clear-cut. Under the international laws of armed conflict, you are entitled to capture and hold until the end of hostilities individuals who are fighting against you. You are not required to charge them with a crime. You are not required to provide them with a lawyer or access to your courts. And you are not required to let them go return to the battlefield and fight against you and prolong the armed conflict and all of the suffering that that inevitably entails.

There are some issues of classification that arise, but we didn't regard those as particularly difficult, either. You do have to decide whether the person you've captured is what's known as a lawful combatant -- and a lawful combatant is entitled to a certain status under international law and has to be treated in a certain way -- or whether the person you've captured is an unlawful combatant; that is, someone who fights by violating the laws, usages and customs of war, and in so doing, presents an unusual and unacceptable threat to civilian populations, and therefore has a lower status under international law and is entitled to many fewer protections.

As it happens, the core group of people that we were worried about, militant Islamic terrorists affiliated with Al Qaeda or otherwise, were clearly unlawful combatants. The requirements under international law for lawful combatancy includes such things as wearing insignia so that you can be clearly distinguished from the civilian population, bearing arms openly, being part of a chain of command that can ensure that you yourself follow the laws of war as you fight, and finally and most importantly, obeying the laws of war yourself, acknowledging that you are bound by them and prevented, for example, from hiding in civilian populations or attacking undefended civilian sites or civilian populations that have no military value. ...

It was clear to everybody that Al Qaeda and the other militant Islamic terrorists were unlawful combatants by virtually any definition and as such were entitled to the lowest level of protection under international law of any category of people involved in an armed conflict. That had implications, too, for the Geneva Conventions, because prisoner-of-war status under the Geneva Conventions is tied to some of the same things as lawful combatancy.

From the very start, our intention was to treat them better than the bare minimums that international law required, because as we understood the requirements of international law with respect to terrorists and unlawful combatants, they were fairly minimal. So we were determined to treat them in all respects humanely and to afford them more rights and more protections and better treatment than they might be entitled to.

Historically, the view under international law a long time ago was essentially the lives of unlawful combatants, terrorists, saboteurs, jayhawkers and the like were forfeit and that they could essentially be summarily executed when captured, as they routinely were during the wars in our nation's earlier history. International law had evolved somewhat from that point, but still an unlawful combatant was in a pretty unenviable position from a legal perspective.

And presumably, just practically speaking, there was a desire to extract information ... about where they're going to hit us next?

Absolutely. One of the imperatives was to be able to effectively interrogate those whom we capture, to interrogate terrorist detainees. Under the Geneva Conventions, you're entitled to interrogate prisoners, but they're under no obligation to furnish any information to you other than their name, rank and serial number. And you are not entitled to offer them any inducements or to impose any sorts of punishments or negative pressures on them designed to convince or coerce them to provide anything more. Had we been forced to operate under those rules with respect to the militant Islamic terrorists we were fighting, I suspect that the intelligence dimension of this war, which most of us regarded as absolutely central to our success and to protecting the American public, would have been far less successful.

So take me into some of the early meetings.

The first thing to bear in mind is that we were all in the weeks and months after 9/11 drinking from a fire hose. The number and the scale of the problems, both domestically and internationally, confronting the president and his staff and the rest of the government were absolutely enormous. And so nobody had time to spend months chewing over things that under other circumstances they might have been inclined to spend months chewing over.

One example of the attention to civil liberties is that the "domestic consequences group" within the White House that was trying to deal with some of the domestic fallout of the attacks -- impact on the airline industry, the impact on the insurance industry, the impact on lower Manhattan and the effort to just recovery physically from the attacks in New York City -- that there was early on for that domestic consequences team a lawyer essentially tasked with trying to make sure that nothing we were doing in our domestic response was going to be discriminatory or constitute an undue abridgement of civil liberties. So there was in essence a kind of watchdog or ombudsman appointed just to keep our eye out for those kinds of issues, to sound