The fear of civil rights groups and others that the U.S. Supreme Court might deal a lethal blow to a key provision of the Voting Rights Act of 1965 appeared to play out in real time on Wednesday in arguments before the justices.

The provision is Section 5, considered the heart of the act. It requires government entities with a history of voting discrimination to have any changes in voting practices precleared, or approved, by the U.S. Department of Justice or the federal district court in Washington. Section 5 currently covers nine states, primarily in the South, and parts of seven others. A formula in Section 4(b) of the act determines which jurisdictions must submit to Section 5.

In Shelby County, Alabama v. Holder, the court is asked whether Congress exceeded its authority under the 15th and 14th amendments when it reauthorized Section 5 under the Section 4(b) formula, a formula that the challengers contend is outdated and intrusive on state sovereignty. The two sections work in tandem and much of the arguments on Wednesday focused on the coverage formula.

Four of the court’s conservative justices voiced strong skepticism about the constitutionality of the act’s Section 5, which Congress reauthorized in 2006 for 25 more years. Justice Clarence Thomas remained silent, although he wrote in a 2009 Voting Rights Act case that he would strike down Section 5. The court’s four more liberal justices appeared supportive of the section’s constitutionality.

Despite sometimes hostile questioning by Chief Justice John Roberts Jr. and justices Antonin Scalia, Anthony Kennedy and Samuel Alito Jr., some civil rights leaders said after the arguments that they are optimistic the court will not leave the job of eradicating voting discrimination "half done."

"The Voting Rights Act was a response to more than 100 years of ignoring the rights of freed slaves to become citizens," said Debo Adegbile, special counsel to the NAACP Legal Defense Fund, who shared argument time with Solicitor General Donald Verrilli Jr. in defense of Section 5."It is not about a special entitlement. It is about inviting everyone to the party of our democracy."

Adegbile’s "entitlement" comment was a response to an exchange between Scalia and Verrilli. The justice recounted how when the law was enacted, Senate votes opposing it were in the double digits. But with each reauthorization, Senate opposition decreased until in 2006, reauthorization was passed with no opposing votes. The House had a similar record, he said.

"Now, I don’t think that’s attributable to the fact that it is so much clearer now that we need this," said Scalia. "I think it is attributable, very likely attributable, to a phenomenon that is called perpetuation of racial entitlement. It’s been written about. Whenever a society adopts racial entitlements, it is very difficult to get out of them through the normal political processes. And I am fairly confident it will be re-enacted in perpetuity unless a court can say it does not comport with the Constitution."

The problem with the reauthorization of Section 5 and the coverage formula in particular, according to Scalia and his conservative colleagues, is that Congress did not adequately justify treating states differently.

When [Congress] reauthorized the act in 2006, Alito asked Verrilli, why wasn’t it incumbent on Congress to make a new determination of coverage using a formula based on up-to-date statistics? "Maybe the whole country should be covered," he said.

Verrilli said Congress was justified in leaving the coverage formula alone, based on the covered states’ history of discrimination as well as recent and ample evidence of voting discrimination in those states. He also said the act provides covered jurisdictions with an escape route—so-called bail out—if they can show no discriminatory policies for 10 years. Bail out, coupled with bail in when judges find new jurisdictions that should be subject to Section 5, keeps the coverage relevant, he argued.

Shelby County’s counsel, Bert Rein of Wiley Rein, reminded the court that in a 2009 decision, signed by eight justices, it had raised serious constitutional questions about Section 5. It also had noted that the record before Congress in 2005 showed that the South had changed, he said.

Justice Sonia Sotomayor immediately interjected, "Your county pretty much hasn’t." She noted that in the period covered by the reauthorization, Shelby County had 240 discriminatory voting changes that were blocked by Section 5 objections.

"Why would we vote in favor of a county whose record is the epitome of what caused the passage of this law to start with?" she asked.

Justice Elena Kagan followed by telling Rein, "Under any formula Congress could devise, it would capture Alabama."

Rein said Shelby County is covered by virtue of Alabama being covered, not because of any independent evaluation by Congress.

"We are here to challenge this formula because, in and of itself, it speaks to old data; it isn’t probative with respect to the kinds of discrimination that Congress was focusing on, and it is an inappropriate vehicle to sort out the sovereignty of individual states. We’re here with a county, a state, that are swept in by a formula that is neither in theory nor in practice rational. That’s the nub of the case."

But Justice Stephen Breyer drew an analogy between voting discrimination and an old disease, saying, "It’s an old disease; it’s gotten a lot better, but it’s still there. So if you had a remedy that really helped it work, but it wasn’t totally over, wouldn’t you keep that remedy?"

Rein argued that Congress has to treat each state with equal dignity. "It has to examine all the states," he said. "When Congress has done that kind of examination, it can devise a formula even if it understands that that formula will not apply across all 50 states."

The nine states covered by Section 5 are Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia. Last May, a 2-1 panel of the U.S. Court of Appeals for the D.C. Circuit upheld the law.

Marcia Coyle is the chief Washington correspondentfor The National Law Journal, a Legal affiliate based in New York.