A St. Paul landlords' lawsuit has been heard in two local federal courts, has been accepted by U.S. Supreme Court justices, and is now back in federal district court. It's a case that raises questions about whether the city of St. Paul properly enforced its housing codes against landlords who rented often run-down places to low income tenants.

But the case also raises a larger concern about the fate of an important principle of antidiscrimination law. It's called "disparate impact" and has been effectively used to promote fair and equitable treatment for the past several decades.

Disparate-impact rules prohibit an institution from using policies or practices that have an unjustified adverse impact on groups that have often suffered discrimination. Those groups include people of color, women, seniors and the disabled. Plaintiffs bringing complaints in such cases must demonstrate that a pattern of behaviors or policies resulted in discrimination.

About a dozen St. Paul landlords used disparate-impact arguments to sue the city of St. Paul, arguing that the city's aggressive housing code enforcement cost them more to make repairs or in some cases forced them to sell their buildings. They claim that the city's actions made them close their properties and force out low-income and mostly minority renters, thus having a disparate, discriminatory impact on those renters. The city counters that the property owners were slumlords who consistently violated housing codes.

A federal district court ruled in favor of the city in 2008, but a three-judge federal appeals court panel reversed the lower court decision and the full court voted 6-5 to ask the Supreme Court to review the case. The high court took the case, but then the city decided to drop the appeal. The circumstances have become controversial, but advocates of civil rights and fair housing, including former Vice President Walter Mondale, a Fair Housing Act author, encouraged St. Paul to withdraw its Supreme Court appeal. Mondale and others feared that the conservative court would use the suit to begin dismantling the disparate-impact principle.

The landlords' twisted application of the disparate-impact concept violates the spirit and intent of the original law. It implies that poor people must tolerate substandard, code-violating housing in order to have housing at all. Authors of the Fair Housing Act never intended to have antidiscrimination rules used to excuse landlords from following basic housing codes.

The disparate-impact principle wouldn't be needed if this nation were bias-free. But as numerous cases demonstrate, it isn't.

Disparate-impact laws were crucial, for example, in the Minneapolis Hollman settlement that prompted the demolition of substandard projects just north of downtown and their replacement with livable mixed-income and senior housing. And a successful local lawsuit showed that people of color were often given harsher sentences for crack cocaine possession than whites received for the same amount of powder cocaine.

Within the past few years, several major banks, including Wells Fargo and Countrywide, reached multimillion-dollar settlements after being accused of discriminatory lending practices. Banking and other business groups are lobbying hard to end the use of disparate-impact analysis.

Current legal debates across the country over voter ID laws -- including the amendment that will be on the ballot in Minnesota next month -- have a disparate-impact element.

Though the U.S. Supreme Court will not hear the St. Paul case, it may soon take up a New Jersey case raising similar issues. A lawyer for the St. Paul landlords said he would push to postpone the Minnesota trial until that case is decided.

To address issues raised in those cases, lawmakers could review discrimination laws and clarify when disparate-impact analysis can be applied. But the principle is still needed and should not be eliminated. Courts at all levels should recognize the continued value of holding institutions, business and government accountable for fair and equitable treatment in housing, employment, lending and voting.

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