Justice Antonin Scalia waits while being introduced before a speech in 2009. (Craig Fritz/AP)

Civil rights activists who came to the Supreme Court on Wednesday expecting a conservative assault on a decades-old law used to fight housing discrimination left wondering whether they had found an unlikely defender.

Although liberals and conservatives on the court squared off as expected, Justice Antonin Scalia was a surprise. A stalwart of the conservative wing, Scalia asked tough questions of the lawyer representing the state of Texas, who asked the court to rule that the protections offered by the Fair Housing Act of 1968 are not as expansive as lower courts have found them to be.

Those courts have found that the act’s anti-discrimination protections extend to policies with a so-called disparate impact. That means that what looks to be a neutral policy on its face has the effect of discriminating against minorities, whether the action was intended or not.

Justice Stephen G. Breyer summed up the liberal argument.

“This has been the law of the United States uniformly throughout the United States for 35 years, it is important, and all the horribles that are painted don’t seem to have happened, or at least we have survived them,” he said. “So why should this court suddenly come in and reverse an important law which seems to have worked out in a way that is helpful to many people, [and] has not produced disaster?”

Texas Solicitor General Scott A. Keller, representing the Texas Department of Housing and Community Affairs, said the Supreme Court has never reviewed those lower courts’ decisions.

He said the text of the FHA prohibits only purposeful discrimination, not disparate impact. The latter is complicated and problematic, the state has argued, and encourages litigation. And it forces states and local agencies to consider racial outcomes in a way that the Constitution says they should not, Keller said.

But Scalia was a tough sell. By the time Congress amended the act in 1988, courts had already found disparate impact applied to the FHA, he said, and lawmakers passed some amendments to the law that seemed to recognize just that.

“Why doesn’t that kill your case?” Scalia asked. He added, “The law consists not just of what Congress did in 1968, but also what it did in ’88. And you look at the whole law . . . and if you read those two provisions together, it seems to be an acknowledgment that there is such a thing as disparate impact.”

At the same time, Scalia said he had difficulty seeing how courts could decide whether a policy has a disparate impact without employing the kinds of race-conscious analysis the court has ruled out in the past.

He questioned Michael M. Daniel, representing a housing advocacy group that had challenged some of the actions of the Texas housing department. A federal appeals court said the group could use statistics to show the effect of the policies.

“Racial disparity is not racial discrimination,” Scalia said. “The fact that the NFL is — is largely black players is not discrimination. Discrimination requires intentionally excluding people of a certain race.”

Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr. were far tougher on Solicitor General Donald B. Verrilli Jr., who was defending the Department of Housing and Urban Development’s position that disparate impact was appropriate to the FHA.

“Is there a way to avoid a disparate-impact consequence without taking race into account in carrying out the governmental activity?” Roberts asked. “It seems to me that if the objection is that there aren’t a sufficient number of minorities in a particular project, you have to look at the race until you get whatever you regard as the right target.”

Roberts was also concerned about how governments would know what kind of action would qualify as disparate impact. Would an agency be challenged for building new housing in a blighted area? It could be argued that such a project would be good for the neighborhood but not promote integration in the way that building it in an affluent neighborhood might.

Verrilli said the answer would be to let courts decide on the specifics facts at hand, not eliminate the consideration of disparate impact.

Verrilli said the court should also follow its usual rules and defer to the interpretation of the agency — in this case HUD — when the law is ambiguous.

Alito pointed out that HUD did not issue regulations until 2013, after the Supreme Court had expressed an interest in the subject. He wondered whether the Obama administration was trying to influence the debate by passing regulations at that time.

“I don’t mean to be flip about it because I understand the import of Your Honor’s question,” Verrilli said, “but I do think it overestimates the efficiency of the government to think that you could get, you know, a supposed rule-making on an issue like this out within seven days.”

The case is Texas Department of Housing and Community Affairs v. Inclusive Communities Project.