I am mystified by the conservative commentators who voice their support for racial profiling as a way to catch terrorist suspects. These pundits support the authorities screening or otherwise keeping a close eye on mainly young Muslim men of North African, Middle Eastern or South Asian descent, because an overwhelming number of terrorists hail from those regions.

But here is where the commentators have me confused. They are well known for arguing that:

* The Constitution, specifically the 14th Amendment, bars the government from creating and enforcing laws that treat people differently simply because of race.

* Individuals should be judged by the same standard regardless of national origin, race or religion.

* The government should not have double standards based on race, ethnicity or religious beliefs.

Conservatives, so I had been given by them to believe, stand foursquare against preferences based on group identity. So how is it that they can support law enforcement policies that, if adopted, would allow people to be treated unequally; give preferences in screening based on race, ethnicity, religion and national origin; and no longer honor the rights of individuals but instead judge individuals by the group to which they belong?

Under racial profiling, as they would have it practiced in subways, airports, train stations, etc., individual differences among North African, Middle Eastern and South Asian young men would be ignored. These people would be labeled and profiled as possible terrorists and be reduced to an amalgamated stew closely watched by the state.

And I thought conservatives believed that the individual should be allowed to go wherever and do whatever he or she wants provided that person isn't breaking any law, hurting anyone or violating any trust. But if I understand the commentators correctly, they would have subway police, airport screeners, railroad agents and police practice discrimination based on group identity even though members of the group are individually without blame.

And what next? The question is germane because eyeballing likely terrorists doesn't come easy. Who among us, for example, can distinguish a Muslim man from a non-Muslim man? A Saudi from a Salvadoran? A dark-brown-skinned Jamaican from a dark-brown-skinned Washingtonian? A heavy coat-wearing, backpack-toting, suicide bomber, quietly reciting religious verse, from the over-cloaked, muttering, bag-laden homeless man who takes off running at the sight of a cop?

Well, here's one way to take the guesswork out of terrorist spotting. All young Muslim men of African, Middle Eastern and South Asian descent, as well as those who look like London's Jamaican suicide bomber, could be required to register with the government.

Oh, yes, one more thing: To help commuters and authorities who are hopelessly unable to recognize the difference between good and bad Muslim men of color, how about making those possible terrorists wear some kind of identification -- say a patch on their shirts with a crescent moon? That way, travelers will immediately know a threat when they see one.

Liberty? Rights? C'mon, what's the U.S. Constitution between freedom-loving Americans? Well, in fact, it is the Constitution that stands against those who would authorize the use of assumptions based on race, ethnicity and religion in law enforcement. It is the Constitution that limits the use of race and ethnicity in law enforcement decisions except in the most extraordinary circumstances. A person's apparent ethnicity, absent a specific threat or a reason to suspect that person poses an extra danger, is no basis for heightened scrutiny. That stance comes from the U.S. Justice Department, which prohibits federal law enforcement from relying on generalized stereotyping. There is no warrant in law for using religion, national origin, ethnicity or race as a proxy for potential criminal behavior.

Are there exceptional instances in which those factors can be considered? Of course. As the Justice Department observed in a June 2003 fact sheet on racial profiling, acting on "specific information, based on trustworthy sources, to 'be on the lookout' for specific individuals identified at least in part by race or ethnicity" does not constitute impermissible stereotyping. But acting on generalized assumptions about people of different races or ethnicities -- or stereotyping certain groups as having a greater propensity to commit acts of terrorism -- does cross the line.

If any collection of Americans should understand the objection to assuming that a person of one ethnicity is more likely to engage in wrongdoing than individuals of other ethnicities, it should be the conservative commentators who decry the notion of group blame or praise. How can they, of all people, argue that the government, in the name of fighting terrorism, should judge individuals differently on account of their national origin, ethnicity, religion or race? Is it because they know it won't be their ox that gets gored?