Emphasis is mine.
"Both the president and Congress have agreed that the United States is at war, and Congress passed an authorization for using force against any groups, nations or people responsible for the 9/11 attacks. Capturing prisoners has been a permanent feature of war throughout human history; hundreds of thousands were detained during World War II alone. Sometimes, unfortunately, the enemy has included U.S. citizens - in the Civil War, every Confederate soldier was a citizen, and in World War II some Americans fought in the Axis armed forces. They never had a right to sue the soldiers who caught them.
We are in a difficult war against an unprecedented enemy. Its members deliberately disguise themselves as civilians and carry out surprise attacks on innocent civilian targets. They do not have a territory, city or population. They are trained to claim abuse when captured and to appeal to the legal system to tie up democracies in knots.It is a difficult job for our government and armed forces to adapt the rules for war to such an unconventional, non-state opponent."
John Yoo is a law professor at the University of California, Berkeley, and a visiting scholar at the American Enterprise Institute and the author of War By Other Means".
He is a supporter of the unitary executive theory and based his arguments for a strong response from the executive branch to terror. Here is an example of this: The War Powers Act.
Most folks wrongly assume that the unitary executive theory is something cooked up the the Bush Administration. It has a long history and has been used by past Presidents. This post, called, What the "Unitary Executive" Debate Is and Is Not About , from the University of Chicago Law School, gives some information on the history of the unitary executive theory.