Several provisions of the PATRIOT Act are due to sunset by the end of this year, all of which are extremely important to our nation in the fight against terrorism.

It is expected that there will be a vigorous debate in Congress this year about those sections, plus one section not due to sunset but that nonetheless has been the subject of controversy both in and out of Congress. That provision, Section 213, pertains to "delayed notification search warrants."

A typical search warrant is obtained by presenting an affidavit, signed by a member of law enforcement, to a magistrate. The magistrate makes a decision whether probable cause to support the search exists, and, if it does, the magistrate issues a warrant. The execution of most search warrants begins with a knock on the door and, shortly thereafter, a delivery or display of a search warrant issued by a court.

However, there are certain occasions when, for legitimate law enforcement reasons, officers do not want to tip off the subject of an investigation that a search is occurring or that an investigation even exists.

If a terrorist or criminal is tipped off, he might injure or kill witnesses, flee, destroy evidence, alert associates or stop communicating and otherwise behaving in ways that law enforcement can monitor or investigate. Moreover, it may be necessary to conduct a search before the conclusion of an investigation or the appropriate time for an arrest.

Recognizing that searches sometimes need to be conducted without tipping off the subject of an investigation, law enforcement has used delayed notification searches for decades, mostly in the drug and organized crime contexts.

This particular law enforcement technique allows a search warrant to be executed without immediate notification of the search being given to the owner or occupant of the place to be searched. Such a search is executed when the owner or occupant is known to be away from the location and is done in such a way as to avoid leaving indications that a search occurred.

Delayed notification searches, conducted pursuant to a warrant and under the supervision of a court, have long been held by the judiciary to be constitutionally valid. In fact, the U.S. Supreme Court approved delayed notification search warrants in the case of Dalia v. U.S. in 1979. The Fourth Amendment, which prohibits "unreasonable searches and seizures," does not require immediate notification of a search or a seizure. Conversely, neither the PATRIOT Act nor the courts allows for an indefinite delay or no notification at all.

Historically, the rules courts applied to their consideration and regulation of these types of searches varied from jurisdiction to jurisdiction around the country. Therefore, the PATRIOT Act provided a uniform set of rules for a longstanding law enforcement practice. Section 213 of the Act requires that the government seek, at the same time the warrant is sought, a court order for a delay in notification. Specific reasons must be demonstrated in support of the request, such as the threat of evidence tampering, witness intimidation or flight, to name a few. Further, the delay in notification must be reasonable and is usually brief.

As a practical matter, these standards mean that this technique will be used only under rare circumstances. A recent survey of U.S. attorneys' offices indicated that only 0.2 percent of all search warrants nationwide involved delays in notification.

Delayed notification searches under Section 213 have been used successfully in the fight against terrorism, as well as in other law enforcement contexts, including drug and child pornography cases. This important law enforcement technique is necessary in the fight against various threats, some old and some new, to the safety and well-being of American citizens.

Without Section 213, law enforcement officers, often on the front lines of the war on terrorism, would find their hands tied and would face an awful choice when considering a search. They would have to choose between conducting a search and thereby possibly putting lives in danger and compromising or ending an investigation, or foregoing the search to preserve the secrecy of the investigation, and passing up whatever useful, perhaps critical, information might be gained from it.

The loss of Section 213 would result in less vigorous investigations, more terrorism, more crime, less safety for our citizens, and possibly injury or death to individuals ranging from witnesses in investigations to the innocent victims of terrorism.

This issue is that important.

We can defeat terrorism without giving up our liberties. We can defeat terrorism without stepping outside the bounds of the Constitution. However, we cannot defeat terrorists by tying the hands of law enforcement.

Thomas E. Johnston is the U.S. attorney for the Northern District of West Virginia. Appointed by President Bush, he has served in that position since Oct. 30, 2001.