ASHINGTON -- America is fighting against "the most evil kinds of people," President Bush said last week, explaining his executive order creating special military tribunals for foreign terrorists. "I need to have that extraordinary option at my fingertips."

But the administration has yet to show where the president gets the authority for this extraordinary executive order. I have called for hearings of the Senate Judiciary Committee, beginning today, to allow the administration the opportunity to explain itself. I am pleased that Attorney General John Ashcroft has agreed to testify before the committee next week.

The president's order says it derives its authority in part from a federal statute requiring that the president, "so far as he considers practicable, apply the principles of law and the rules of evidence generally recognized in the trial of criminal cases in the United States district courts."

The order allows evidence to be admitted without regard to the normal rules of a criminal trial if it is deemed to have "probative value to a reasonable person." It permits conviction by a two-thirds vote of the majority of the military commission hearing the case. The order also specifically prohibits any proceeding in federal courts or any other court and allows for review only by the president or secretary of defense.

The administration argues that these constraints are necessary. "Given the danger to the safety of the United States and the nature of international terrorism," applying normal rules of justice "is not practicable," according to the president's order. But the order itself contains precious little rationale for suspending such rules.

Simply declaring that applying traditional principles of law or rules of evidence is not practicable is hardly sufficient. The usual test is whether our national security interests outweigh our due-process rights, and the administration has not yet made this case. In doing so, it would have to explain how so many terrorists have been convicted in our federal courts using time-honored criminal procedures.

Since the Constitution empowers the Congress to establish courts with exclusive jurisdiction over military offenses, some consultation with leadership before the promulgation of the order would have been appropriate. No member of the Senate Judiciary Committee, to my knowledge, was consulted or even notified in advance of this order.

Congress has fully cooperated with the president in the war against terrorism with legislation authorizing the use of force and the appropriation of billions of dollars at the president's request. We promptly passed a statute, in public and with detailed rationale available in the Congressional Record, broadening law enforcement powers to fight terrorism.

It may be that the executive branch can justify the extraordinary and far-reaching powers called for in the order. However, even in war, Congress and the courts have critical roles in establishing the appropriate balance between national security and civil rights. We should not forget that decades after interning United States citizens of Japanese extraction, the government apologized and paid reparations.

Vigorous Congressional oversight is the indispensable first step in determining what is "practicable" in finding that balance.

Arlen Specter, Republican of Pennsylvania, is a member of the Senate Judiciary Committee.