Charles Krauthammer's endorsement of the profiling of "young Muslim men of North African, Middle Eastern and South Asian origin" ["Give Grandma a Pass," op-ed, July 29] restated the misguided belief that using racial or ethnic appearance as a factor in deciding who merits police suspicion makes for good law enforcement. He is mistaken. Using race or ethnicity this way will not make us safer; it will make us less safe.

In a war against terrorism, we must train our law enforcement personnel to watch for the things that terrorists do, no matter what they may look like. The Israeli aviation security system has made this a guiding principle. Our certainty about what our enemies "look like" distracts our security forces from what's important: terrorist behavior. The result is less accuracy.

In addition, the inclusion of people who "look like" our enemies results in a huge number of false positives upon which we spend our precious time and resources.

Perhaps most important, when we focus on Muslims from the Middle East, North Africa and South Asia, our ability to receive intelligence from these groups will be corroded because these people will begin to fear law enforcement. And fear will cut off communication and our best source of human intelligence on potential sleeper cells in the United States.

Contrary to what Mr. Krauthammer said, profiling will not leave our murderous enemies with the single alternative of "recruiting elderly Norwegian women." Al Qaeda has shown itself to be smart, adaptable and cunning; it will simply use people who do not play into our stereotypes. The appearances of people from the Middle East, North Africa and South Asia vary enough that these killers won't be held up for a minute.

Avoiding racial or ethnic profiling is not a matter of "assuaging the feelings of minorities" or of political correctness. It is about avoiding a tactic that would be profoundly against our own interests.

DAVID A. HARRIS

Toledo

The writer is a law professor and the author of a book on racial profiling.