In 1971, along with the late Rep. Spark Matsunaga and others in the House of Representatives, I sponsored the Non-Detention Act, which states: "No citizen shall be imprisoned or otherwise detained by the United States except pursuant to an Act of Congress."

This simple provision of law has served as a bulwark against the United States' ever again establishing internment camps for citizens -- as it did during World War II -- without the acquiescence of Congress. It also stilled the concern occasioned by a McCarthy-era statute that authorized some camps (which were never opened) to hold those engaging in riot or insurrection. The purpose of the Non-Detention Act was clear: to prevent the executive from detaining U.S. citizens without explicit statutory authority.

Recently the Supreme Court considered the Non-Detention Act in the case of Yaser Esam Hamdi, a U.S. citizen taken prisoner in Afghanistan while allegedly fighting for the Taliban. Justice Sandra Day O'Connor wrote that "a state of war is not a blank check for the President when it comes to the rights of the Nation's citizens."

But did an act passed by Congress shortly after Sept. 11, 2001, provide the president with the statutory authorization to detain U.S. citizens that was required under the Non-Detention Act?

Justice David Souter stated that the post-Sept. 11 law -- the Authorization for Use of Military Force -- is "fairly read to authorize the use of armies and weapons, whether against other armies or individual terrorists." But this act never uses the word "detention," and, Souter wrote, there is "no reason to think Congress might have perceived any need to augment Executive power to deal with dangerous citizens within the United States, given the well-stocked statutory arsenal of defined criminal offenses covering the gamut of actions that a citizen sympathetic to terrorists might commit."

Although Congress gave the president the power to use military measures to fight terrorism, it did not strip U.S. citizens accused of terrorist activities of the protections of citizenship. U.S. citizens accused of involvement in terrorist activities should be charged with a specific crime or released -- not held indefinitely.

The lesson of history is that if Congress is going to authorize the detention of American citizens for indefinite periods, it needs to do so directly and intentionally, so that it can be held accountable. Why? Because executive detention is a dangerous power that otherwise can too easily be abused, as the Japanese American detention camps showed in World War II.

Our more recent history shows that many are being detained based on suspicion of involvement in a terrorist conspiracy. Some were released after a period of detention, without any charges being filed. Others, such as Hamdi or a Chicago suspect named Jose Padilla, accused of plotting to detonate a "dirty bomb," are still being held. Today, after the Hamdi decision, such persons have limited right to access to counsel and some ability to challenge in court the factual determination of whether they can be deemed "enemy combatants." But they lack the basic right to know the charges against them or to receive a host of assurances of due process available even to a U.S. citizen charged with treason.

The principle at the heart of the Non-Detention Act was affirmed by Justice Antonin Scalia, who wrote (with Justice John Paul Stevens's support): "The very core of liberty secured by our Anglo-Saxon system of separated powers has been freedom from indefinite imprisonment at the will of the Executive." As O'Connor observed, "It is during our most challenging and uncertain moments that our Nation's commitment to due process is most severely tested; and it is in those times that we must preserve our commitment at home to the principles for which we fight abroad."

Thirty-three years ago Congress expressed the same vision with the plain words of the Non-Detention Act. The Supreme Court has left it to the lower courts to decide on a case-by-case basis whether the Authorization for Use of Military Force or future congressional enactments satisfy the requirements of the Non-Detention Act and give the executive branch the right to detain American citizens. I hope the courts will set the bar high and prohibit the detention of U.S. citizens by the executive unless Congress specifically authorizes such detention. And I hope Congress will take care in the future to avoid the kind of ambiguity the Supreme Court found to exist in the military force act. Finally, I hope this president will return to the traditions that have made our democracy strong and realize that if he believes he needs additional powers to fight terrorism, he should make that case to Congress and the people.

The writer was a Democratic representative from Illinois and later served as chief judge of the U.S. Court of Appeals for the D.C. Circuit and as White House counsel. He is a visiting professor at the University of Chicago Law School.