Still, the progress is undisputed. And for supporters, that's left them with fewer violations to justify the measure and making the case that the requirements still are needed.
"Like any other law," Persily wrote, "Section 5's effectiveness should not be evaluated by the number of times it is broken."
Much of the force behind the renewed push against Section 5, though, comes from those who argue that the federal government -- the Justice Department, in particular -- is overly activist and discriminatory in its own right, because it treats states differently.
"When this law passed in '65 it was a five-year emergency. The Super Bowl didn't even exist when this law passed," says Christian Adams of the Election Law Center. "You have to ask the question: Is this much federal power justified under these circumstances?"Perhaps aside from the current case, nowhere have those battles gained more attention than in the recent fights over voter ID that landed both South Carolina and Texas in court battling the Justice Department for the right to enact such laws. Those two states are among the 16 states that are entirely or partially covered by the preclearance requirement.
Each case shows how the Voting Rights Act works in practice, rather than just on paper.
After months of court battles and back-and-forth with the Justice Department, South Carolina eventually won the right to enact its voter ID requirement. But in the process, it was delayed until 2014, and its strict requirements were significantly loosened, an outcome voting rights activists said illustrated the still-relevant benefits of the law.
Texas, meanwhile, refused to adopt a similarly cooperative tack, and saw its law denied. In its ruling, a three-judge panel in the Washington, D.C., federal court faulted the state for its overly strict law and said it would "almost certainly have retrogressive effect" on minority voters.
Texas officials blasted the ruling as both an encroachment on their state's right to govern its elections and as discrimination, since the Supreme Court has generally upheld voter ID requirements to be constitutional. The state has since issued a brief backing Shelby County's case against the law.
It's those disputes that voting rights advocates have been highlighting in advance of the Supreme Court arguments, sounding the alarm about the potential doom for the provision and calling the entire case an attack on voting rights. They point to typically Republican-backed provisions around the country on voter ID requirements, limiting early voting or other such barriers.
"There are still politicians who, perhaps it's not out of racial animus but perhaps it's because they're afraid certain populations will vote a certain way, look to manipulate voting laws," says Spencer Overton, an election law expert at George Washington University.The prospect of going on without Section 5's bulwark of federal power worries advocates. Any election law can be challenged, but preclearance is a particularly powerful tool.
"Recent developments, and especially these new obstacles to voting, make the Voting Rights Act more important than it might have seemed even a decade ago," Daniel Tokaji, a law professor at Ohio State University. "We've seen pretty blatant attempts in some states to impose new barriers to voting."And even as the Supreme Court weighs the case before it, there's little sign the dispute is diminishing elsewhere.
Just last week, the Virginia General Assembly approved a strict voter ID requirement that opponents have vowed to fight in court. For the time being, they can take comfort in the fact that it won't take effect until the state proves it wouldn't negatively affect voters. That's because Virginia is one of the states covered by the preclearance requirement of the Voting Rights Act -- at least for now.