Look, it’s an illegal, right?

If Arizona’s Republican legislators weren’t so dumb, they’d be dangerous. Or maybe they’re dangerous because they’re dumb.

Either way, once they stop celebrating the passage of what should be dubbed the “We really, really, really don’t like illegal aliens” bill , they’re going to have to figure out how law enforcement is supposed to identify the culprits.

It’s always fun to read the text of silly legislation. Turn to Section 2, Paragraph B, which states: “For any lawful contact made by a law enforcement official or agency of this state or a county, city, town or other political subdivision of this state where reasonable suspicion exists that the person is an alien who is unlawfully present in the United States, a reasonable attempt shall be made, when practicable, to determine the immigration status of the person.”

Did you catch the part about “reasonable suspicion”? How is a cop going to know by sight who is or isn’t legal? What about a person will elicit suspicion?

Opponents of the measure argue that the open-ended nature of “reasonable suspicion” will lead to widespread racial profiling of all Latinos. They’re probably overstating their case. Something tells me someone who looks like, say, blond Mexican pop singer Paulina Rubio won’t be stopped.

The truth is that Mexicans are hard to racially profile. Five hundred years of racial mixture has given many Mexican families a decidedly kaleidoscopic racial quality. To wit: Not everyone with Mexican ancestry shares the same skin color.

The law’s proponents say that it’s not about race anyway, it’s about legality, but that isn’t entirely true either. Presumably, certain physiognomic features will stand out. And presumably so will class signifiers and certain ethno-cultural accoutrements.

We can safely assume that most illegal immigrants in Arizona are of humble origins, right? So, should the police “reasonably suspect” people with darker faces? What about fair-skinned Mexicans? Are work boots or jeans a dead giveaway? Would someone draw more suspicion driving a truck or an Audi? Do those “Yo heart Jalisco” bumpers scream “illegal alien”?

And what about accents? Is there a marked difference between the accents of a legal and an illegal immigrant? Should a legal immigrant refrain from blasting ranchera music from his Toyota for fear of being “reasonably suspicious”? It’s easy to imagine this law creating a climate in which both foreign- and native-born legal residents try to avoid being targeted by suppressing any outward signs of ethnicity.

Last Wednesday, Joe Arpaio, the cartoon-like sheriff of Arizona’s Maricopa County — he was wearing a gold tie tack depicting a semiautomatic pistol — assured a CNN anchor that he and his deputies “know the criteria when we come across people who may be here illegally in the country.”

I’d love to see the criteria. Maybe he could set up a hotline, so everyone can be on the lookout for real illegals.

I’m not saying the new law won’t help catch and deport some illegal immigrants. But at the very least, the “reasonable suspicion” clause suggests that the process will be hit or miss, and that plenty of legal residents could be wrongly suspectedand generally harassed. Proponents might say that that’s a reasonable risk to run, but I’m pretty certain that most of them won’t be subjected to the indignities of having their right to be in this country questioned.

It also puts law enforcement in the awkward position that Southern train conductors once faced, fretting over whom they could risk offending. Booker T. Washington writes about the dilemma in his 1901 autobiography. He describes a conductor inspecting a light-skinned passenger seated in the “colored” compartment. The official examines the man’s eyes, nose and hands. If the rider is black, he doesn’t want to send him into the white coach. If he is white, he doesn’t want to insult him by asking his race. To solve his quandary, the conductor bends over to glance at the man’s feet. At last he is convinced the passenger is seated among his own kind.

I guess you could say that Arizona has sent its state law enforcement officers down the road to becoming America’s latest foot soldiers. In the process, they’ve also made their state a little bit more like that segregated train car Washington once rode in.

grodriguez@latimescolumnists.com