Editor's note: Today, John Yoo and Bruce Ackerman interpret the U.S. Constitution for answers to the struggle between the executive and legislative branches over the conduct of the war in Iraq. Later this week, they'll debate the ongoing use-of-force resolution, the hypocrisy of the left and the right on this issue, the questionable relevance of "letters of marque and reprisal" in the 21st century, and the possibility that there may be more important issues here than constitutional language. In this installment, Yoo responds to Ackerman's argument.

Visiting Fellow John Yoo

I agree with your basic point that Congress has the constitutional authority to check the President in wartime. I do not know of anyone who says Congress cannot. But the important question is how.

During the last two centuries, neither presidents nor Congress have ever acted under the belief that the Constitution requires a declaration of war before the U.S. can engage in military hostilities abroad. Although this nation has used force abroad more than 100 times, it has declared war only five times: the War of 1812, the Mexican-American and Spanish-American Wars, and World Wars I and II.

Without declarations of war or any other congressional authorization, presidents have sent troops to oppose the Russian Revolution, intervene in Mexico, fight North Korean and later Chinese Communists in Korea, remove Manuel Noriega from power in Panama, and prevent human rights disasters in the Balkans. Other conflicts, such as both Persian Gulf Wars, received "authorization" from Congress but not declarations of war.

Common sense does not support replacing the way our Constitution has worked in wartime with a radically different system that mimics the peacetime balance of powers between President and Congress. If we were talking about the environment or Social Security, I would agree with you that the Constitution requires that Congress enact the laws that make policy and that the President's job is to faithfully implement the law.

But the Constitution does not give Congress the dominant hand in war. Instead, our framers decided that the president would play the leading role. You are right that the revolutionaries in 1776 rejected the royal prerogative, and they tried out all kinds of experiments to weaken the executive branch. But when the framers wrote the Constitution eleven years later they restored an independent, unified chief executive with its own powers.

The most important of these powers is to wage war as commander-in-chief and chief executive. "The direction of war implies the direction of the common strength," Alexander Hamilton wrote in Federalist 74, "and the power of directing and employing the common strength forms a usual and essential part in the definition of the executive authority."

You do not have to follow Hamilton simply because he was a framer, but because he displayed uncommonly good sense. Hamilton argued that the president should manage war because he could act with "decision, activity, secrecy, and dispatch." "Energy in the executive is a leading character in the definition of good government," he observed. "It is essential to the protection of the community against foreign attacks."

You are right to quote Congress's power to declare war and to pass laws to govern and regulate the armed forces. But presidents and congresses have never believed they allow for control of tactics and strategy. Congress' real power is its power of the purse, not any right to dictate which units should fight where, or whether to surge troops into Baghdad. Congress is too fractured, slow, and inflexible to micromanage military decisions that depend on speed, secrecy, and force.

If Congress feels it has been misled in authorizing war, or it disagrees with the President's decisions all it need do is cut off funds, either all at once or gradually. It can reduce the size of the military, shrink or eliminate units, or freeze its supplies. Passing non-binding benchmarks or playing games with troop readiness won't do the trick. Instead, these ideas show only that Congress wants to pretend it is trying to end U.S. involvement in Iraq, without proposing any serious strategy in its place.

John Yoo is a visiting fellow at AEI.