Arizona has never needed Sen. John McCain more — the "maverick" version of years gone by, that is. The man who understood the inherent evil of demonizing groups of people. The McCain who stood up to strident voices, understanding that fear-based, reactionary sentiments must never be codified into punitive laws.

His state has enacted just such a law, a harsh immigration-enforcement measure that basically equates Latinos with illegal immigrants. Under the legislation signed by Gov. Jan Brewer on Friday, police would be required "when practicable" to detain anybody about whom there is "reasonable suspicion" that they are in this country illegally. Immigrants would be required to carry documents showing they are in this country legally; those who do not produce such documents could be charged with a misdemeanor. Finally, if the police in any jurisdiction choose not to enforce the law with sufficient zeal — and many law enforcement authorities in Arizona are loath to do so — they could be sued.

Arizona — the nation, really — needs a Republican leader of the kind McCain used to be. The kind of man who once co-sponsored a sensible set of reforms for the nation's immigration laws.

Here's how McCain once gracefully silenced a political opponent's demonization of Hispanic immigrants: "So let's from time to time remember that these are God's children. They must come into the country legally, but they have enriched our culture and our nation as every generation of immigrants before them."

That was 2007, as McCain was campaigning in the Republican presidential primary. Today, McCain is a skittish U.S. senator desperately trying to hang onto his seat — so desperately that he is willing to look the other way as civil rights protections are eroded for a large number of his constituents.

Arizona is 30 percent Latino, so this law is sure to wreak havoc. It will impose on police the duty to sift the legal Latino population — the vast majority — from the illegal. Imagine how this will affect Latinos' willingness to cooperate with police.

Note that police already routinely check the immigration status of those they arrest for other crimes. This law directs police to stop people merely on the suspicion that they're illegal immigrants.

U.S. Rep. Luis V. Gutierrez, D-Ill., termed the coming storm "open season on the Latino community in Arizona," and rightly pointed out law enforcement's less than stellar record of restraint when encouraged to profile whomever they please. In a statement, Gutierrez raised the real-world consequences of such a misguided law: "I am Puerto Rican, I was born in Chicago, and my family has been U.S. citizens for generations, but look at my face, listen to my voice: I could get picked up. Is this what we want in America?"

McCain's assessment: "I think it's a good tool."

Some moderate Republicans have misgivings about the law. "We are going to look like Alabama in the '60s," Arizona state Rep. Bill Konopnicki admitted to The New York Times. Of his fellow Republicans he said "everybody was afraid to vote no on immigration."

McCain has acknowledged as much, too. He concedes the punitive law stems from frustration in this border state that was rocked last month when a rancher was shot and killed, possibly by an illegal immigrant with ties to drug cartels.

McCain's problem is that he is running neck-and-neck in the Republican primary with J.D. Hayworth, a right-wing demagogue who has never been afraid to make hay out of popular fears about Hispanic immigrants. In 2005, Hayworth called for banning even legal immigration from Mexico, and he is given to tirades about maintaining the culture of the U.S. against invasions of people he's certain won't assimilate.

Rather than sticking to his principles, his vast broad knowledge of the complicated nature of immigration law, McCain appears content to step into the swill with Hayworth. What a contrast McCain presents to the Southern politicians who stood up for segregation in the 1950s and '60s but then, pricked by their consciences, lamented being on the wrong side. McCain, a politician known for principle and courage, seems headed in the other direction.

And for this he is expecting the good people in Arizona to vote for him?

Mary Sanchez is an opinion-page columnist for The Kansas City Star.