Forty-eight years ago, exasperated with the persistent abuse of black voters, Congress put most of the American South in a timeout. Now the Supreme Court appears poised to end those sanctions.

It shouldn’t. But that doesn’t mean the selective scrutiny applied to Southern states is necessarily fair. As the justices consider the case of Shelby County v. Holder, which was argued before the court Wednesday, they should keep in mind one goal above all others: protecting the right to vote, regardless of region or other circumstances.

The Voting Rights Act of 1965 bans discriminatory voting procedures nationwide, codifying the 15th Amendment’s guarantee of the right to vote regardless “of race, color, or previous condition of servitude.” The law has stricter requirements, however, for jurisdictions with a long history of disenfranchisement.

One of these jurisdictions is Shelby County, Ala., which is required to get federal approval (or preclearance) for any change, however small, to its voting procedures. In 2010, arguing in part that all states should be treated equally, Shelby County sued to prevent the Justice Department from enforcing this provision.

Shelby County’s argument, echoed by similarly targeted jurisdictions, can be reduced to two points: First, we’ve learned our lesson. Second, other places, including many not subject to the preclearance requirement, are worse.

Justice Anthony Kennedy appeared sympathetic to this point, asking why Congress still needed to “single out” some states. And Chief Justice John G. Roberts neatly summed up this view in an opinion four years ago that upheld the law while all but inviting Shelby County’s lawsuit. “Things have changed in the South,” Roberts wrote.

Yes, they have. There is vastly greater minority representation in Congress and in state capitals now than 50 years ago. Part of the reason for this success is the Voting Rights Act itself, which forced change on entrenched interests.

There is no question that preclearance places both a burden and a stigma on covered jurisdictions. When Congress passed the Voting Rights Act, it knew it was taking an extraordinary step. So it said it would review the statute in five years, adjusting it as necessary.

Meanwhile, the issue of voting rights has grown more complex. In the 2012 election, one of the most egregious attempts to limit voter participation took place in Pennsylvania, which is not covered by the special provisions of the Voting Rights Act. So why is Shelby County subject to federal preclearance when Pennsylvania is not?

This disparate treatment gives the Supreme Court an opening. It could tell Congress that it’s not allowed, as a general policy, to impose different rules on different regions. It could find this particular set of rules antiquated and order Congress to update it. The court could also decide not to intrude on Congress’s decision, made just seven years ago, to extend the Voting Rights Act in its entirety.

Or the court could take a more universal view of voting rights, including but not limited to the issue of racial discrimination. Problems with registration procedures, poorly trained poll workers, inadequate voting hours, accessibility and other factors impede voting for millions of Americans across many states.

The Shelby County case is an occasion to acknowledge how widespread these problems are and to instruct Congress to remedy them. The Voting Rights Act, flawed though it may be, has been an essential tool in the advance of American democracy. But the promise of universal suffrage remains unfulfilled.

So maybe the question isn’t whether it’s time to end the federal government’s special oversight of the South. It’s how to extend that level of attention to the whole country.

Bloomberg News (Feb. 28)