The results of Tuesday's U.S. Department of Housing and Urban Development national study on the persistence of housing discrimination are unlikely to shock: Racial and ethnic minorities continue to find themselves locked out of many housing opportunities.

No, the more startling thing may be what HUD intends to do with its findings. HUD spent $9 million to contract with the Urban Institute to conduct 8,000 undercover tests in 28 metropolitan areas in order to expose illegal housing discrimination. Yet the federal agency has no plans to use these tests to actually enforce the law and punish the offenders.

Once a decade for the last 40 years, HUD has produced a massive survey to reveal the pervasive discrimination that, year after year, exists in America's housing marketplace. But as ProPublica reported late last year, HUD as a policy refuses to invest the same kinds of time, resources and techniques in prosecuting those guilty of the very discrimination its expensive studies uncover. Instead, HUD outsources testing used to find and punish discriminatory landlords to dozens of small, poorly funded fair housing groups scattered across the country.

And Congress has shown little appetite for forcing HUD to do more meaningful enforcement. A bill that would create a national testing enforcement program at HUD is expected to soon die in committee for the third time.

In an interview Tuesday, Housing Secretary Shaun Donovan defended both the decision to conduct the survey and the Obama administration's commitment to ending the kinds of discrimination it revealed.

"The level of investment in fair housing enforcement has been significantly increased by this president," Donovan said.

Because housing discrimination these days is often more subtle — the survey released Tuesday said the kind of "door slamming" racism of years past had declined — testing is considered the best means of uncovering illegal behavior by homeowners, landlords and real estate agents.

According to HUD — the chief enforcement agency of the 1968 federal Fair Housing Act — running its own national testing program to pursue violators would compromise the agency's neutrality. Critics, including the man who created the fair housing testing enforcement program at the U.S. Department of Justice, called that stance "absurd."

In the study released Tuesday, the Urban Institute sent paired testers, one white and one a member of a minority group, to contact housing providers who'd recently advertised homes and apartments. The pairs shared similar stories with the providers about their qualifications and then recorded their treatment.

The good news is the testers — who all presented themselves as highly qualified — found little discrimination when trying to make an appointment to view a home or apartment. Black renters calling about an advertised unit are far less likely to be told it's unavailable than a decade ago.

But the study found significantly different treatment once testers met with agents.

Black, Asian and Latino testers were consistently shown or told about fewer units.

For example, white homebuyers were shown nearly 20 percent more homes as equally qualified black and Asian homebuyers. In one test, a real estate agent refused to meet with the black tester until she was prequalified by a lender but made an appointment with the white tester without asking for prequalification.

Donovan said the findings revealed a "sad" truth that the long struggle to end housing discriminations continues. "Although we've come a long way from the days of blatant in-your-face injustice, discrimination still persists. Any time freedom of choice is attacked it is a threat to the ideals we all value — equality and fairness," he said.

Donovan said these findings represent more than just numbers, and underscore, for instance, a family's inability to move across town to a safer neighborhood with better schools. That the discrimination is "hidden doesn't mean it is any less harmful," he said.

Margery Austin Turner of the Urban Institute said the discrimination uncovered in the study likely understates the problem because buyers presented themselves as highly qualified and did not necessarily represent the typical prospective minority home buyer.

"The discrimination that persists today matters," she said. "Not only is it fundamentally unfair that somebody doesn't find out about available housing because of the color of their skin, but it also really raises the costs of housing searches for minorities. It restricts their housing choices."

Turner recommended increased testing, including at the national level, and strong enforcement.

The agency's unwillingness to fund an internal testing program to not just study but to enforce the 45-year-old Fair Housing Act enforcement has long been criticized as part of its overall failure to address wide-scale housing discrimination.