Arizona's harsh and controversial immigration law, argued before the Supreme Court on Wednesday, goes too far in important ways. But there's no denying the facts that led to its passage: Washington ignored a rising tide of illegal immigration, leaving states and cities to deal with overcrowded schools and emergency rooms and other costly consequences. Over decades the tide became a flood, and states reacted, beginning with Arizona.

The constitutional issue before the court is fairly narrow: whether states are pre-empted from writing their own immigration laws. The Obama administration tried to make the case that Arizona's law is an invasion of federal power, but the justices didn't seem to be buying it. At one point, even liberal Justice Sonia Sotomayor noted that the government's argument was "not selling very well."

Indeed, it's hard to make the case that states and cities should have no right to protect themselves from the consequences of federal inaction. States can't negate federal laws, but there are productive ways for them to cooperate with federal authorities, particularly in the workplace, because jobs are the main magnet that draws illegal immigrants here. The drafters of Arizona's law ― four key parts of which have been suspended by lower courts ― contend they took great care to track federal law and seek only to help enforce it. And if that's the way it all works out, well and good. But the law is so prone to abuse that less rosy scenarios seem more likely.

The most controversial provision requires police to determine the immigration status of people they stop ― for a traffic violation, for example ― when they have a "reasonable suspicion" the person is here illegally. Though the law prohibits racial profiling, the statute also seems to invite it. Would an officer check the status of a white teenager as readily as a dark-skinned Hispanic? That issue was excluded from the court case.

For example, Alabama seeks to clear its classrooms of the children of illegal immigrants by requiring their students to report their parents' immigration status ― which punishes kids who have no say in where they live and who could well be U.S. citizens by birth. Because of the impact on families and businesses, Alabama's legislature is already rewriting the state's law.

The stated goal of such laws is "attrition through enforcement." And that's the real problem. They can succeed only by creating a climate of fear that affects all Hispanics, or perhaps all immigrants, not just those who are here illegally.

In a cold-blooded interpretation, this can be dismissed as just the latest step in the messy process of democracy. It certainly is nothing new. Each past great wave of immigration was greeted with similar ham-handedness. Each time, the flood was staunched, but through an indulgence of bigotry that should be unacceptable.

The alternative is no secret. Washington should do its job: seal the border, sanction employers who hire illegal immigrants, and allow temporary visas for jobs such as migrant farm work. Then provide a path to legality ― one that has to be earned ― for the illegal immigrants already here who work and stay out of trouble.

A succession of presidents has proposed such plans only to see them die along with countless other things in an angry, dysfunctional Congress.

So for now, this obnoxious fight will rage on in courts and in communities, with a heavy toll to be paid by immigrants and citizens alike.

This article was published and distributed by USA Today.