The Obama administration and civil rights groups acknowledge the progress, but also argue that Congress was justified in maintaining the advance approval, or preclearance, provision when the law was last renewed in 2006.
Advance approval has been successful because it requires the governments to demonstrate that their proposed election changes will not discriminate, the law's advocates say. "It moved the burden from victims to perpetrators," said Sherrilyn Ifill, the head of the NAACP Legal Defense & Educational Fund.
Just last year, federal judges in Washington refused to sign off on two separate Texas plans to institute a tough photo identification law for voters and redistricting plans for the state's congressional delegation and Legislature. Also, South Carolina's plan to put in place its own voter ID law was delayed beyond the 2012 election and then allowed to take effect only after the state carved out an exception for some people who lack photo identification.
Opponents say those examples should not be enough to save the measure. Advance approval is strong medicine that has been upheld in the past as an emergency response to longstanding discrimination, lawyer Bert Rein said in his brief for Shelby County.
Congress overstepped its authority when it renewed the law and its formula that relied on 40-year-old data, without taking account of dramatic increases in the voter registration and participation by minorities, or of problems in places not covered by the law, Rein said.
The advance approval was adopted in the Voting Rights Act in 1965 to give federal officials a way to get ahead of persistent efforts to keep blacks from voting.
The provision was a huge success, and Congress periodically has renewed it over the years. The most recent time was in 2006, when a Republican-led Congress overwhelmingly approved and President George W. Bush signed a 25-year extension.
The requirement currently applies to the states of Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia. It also covers certain counties in California, Florida, New York, North Carolina and South Dakota, and some local jurisdictions in Michigan and New Hampshire. Coverage has been triggered by past discrimination not only against blacks, but also against American Indians, Asian-Americans, Alaskan Natives and Hispanics.
Among the covered states, Alabama, Alaska, Arizona, Georgia, South Carolina, South Dakota and Texas are siding with Shelby County, while California, Mississippi, New York and North Carolina argue that the law should be upheld.
Nearly 250 of the 12,000 state, county and local governments covered by the law have used an escape hatch to get out from under the special oversight by demonstrating that they and smaller places within their borders no longer discriminate in voting.
Thousands more jurisdictions also may be eligible, said voting rights expert Gerry Hebert. But that list probably does not include Shelby County, because one of its cities, Calera, defied the voting rights law in 2008 and provoked intervention by the Justice Department in the Bush administration.
A decision is expected by late June.
The case is Shelby County, Ala., v. Holder, 12-96.