Obama doesn't want a landmark civil rights law to die on his watch—so he's letting it wither away.

When Georgia’s Republican leaders redrew the state’s election-district maps last year, Democrats and minorities instantly cried foul. In an increasingly diverse state where 47 percent of voters chose Obama in 2008, the new maps looked likely to hand the GOP 10 of the state’s 14 seats in Congress. Perhaps even more significantly, they were drawn so as to give Republicans a shot at a two-thirds majority in both chambers of the state legislature, allowing them to pass constitutional amendments unilaterally. They achieved this in part by “packing” the state’s black voters (who overwhelmingly vote Democratic) into a handful of districts in order to make others more solidly white (and Republican).

Fortunately for the state’s Democrats, federal law seemed to offer a time-tested remedy. Section 5 of the Voting Rights Act, a landmark civil rights bill passed in 1965 to crack down on poll taxes and other discriminatory practices, requires Georgia and a number of other Southern states to get federal approval for any changes to their voting laws. Any that harmed minorities’ chances of fair representation were to be thrown out. And that’s exactly what Georgia Democrats expected Obama’s Department of Justice to do with Republicans’ new maps. Just two years earlier, it had invoked Section 5 to block two Georgia voter-verification laws. Liberals gleefully predicted the Republican gerrymanders would likewise be “DOA at the DOJ.”

The Republicans held a trump card, however: the threat of a lawsuit challenging the Voting Rights Act itself. If the Justice Department didn’t clear their maps, they warned, they’d pursue their case and seek to have the VRA’s Section 5 struck down by the Supreme Court.

Five years ago, that threat might have rung hollow. Yet the DoJ quickly approved the maps. The state’s Democratic and black leaders were stung by what they saw as a capitulation. “The DoJ’s decision was disappointing, because Republicans took it as an approval of their resegregation strategy,” says Stacey Abrams, leader of the Democratic minority in the Georgia House. So why did the DoJ acquiesce?

It’s possible, of course, that it thought the maps were just fine. While many believe packing contradicts the spirit of Section 5, it’s not prohibited per se. If anything, it provides near-certainty that at least some minorities will be elected to Congress and the statehouse. In Georgia, it’s white Democrats who are likely to be squeezed out as previously diverse districts become whiter and more conservative. The upshot is that black legislators may end up as a powerless Democratic minority in the Statehouse. So is that racial discrimination, or just gerrymandering as usual?

But Georgia is not the only state where the DoJ has disappointed Democrats by signing off on Republican-drawn redistricting maps. Virginia, South Carolina, and Louisiana all got green lights after adopting the same stance as Georgia: Approve or we sue. For Louisiana, it was the first time its state House of Representatives maps had ever won approval on the first try. And last month, the assistant attorney general for civil rights hinted the department might drop its Section 5-based challenge to a North Carolina town’s election law.

The real reason for that laissez-faire approach, Democratic leaders suspect, is that the DoJ is loath to test Section 5 in court. If so, there’s good reason for its reticence. Over the past few years, the law has come under assault from conservatives across the country, who see it as an outdated federal intrusion on state’s rights. The movement has been emboldened by the John Roberts-led Supreme Court, which in 2009 stopped just short of overturning it. The talk among legal experts now is that it may not survive another frontal assault. The obvious conclusion is that Attorney General Eric Holder is picking his Section 5 battles in a bid to spare a vulnerable law from destruction.

But to call Section 5 “vulnerable” is to understate what is already happening in Georgia and other Southern states. A more sober appraisal would be that Holder is trying to salvage what’s left of the VRA: By shying from the redistricting cases, the DoJ has already signaled that it is no longer willing to defend a robust interpretation of the law. Instead, it has focused its efforts on a South Carolina voter ID law, which many see as a straightforward affront to Section 5, and a lawsuit from Shelby County, Ala., that explicitly seeks judicial review of the section.

The restraint may be prudent, but it also comes at a huge cost for Democrats. The maps in states such as Georgia will shape elections there for the next decade, dampening Democrats’ hopes of turning the state blue as its demographics continue to become more diverse. DoJ-approved maps in North Carolina are an immediate setback in a state that voted Democratic in the 2008 presidential election for the first time since 1974.

And even with the Department of Justice carefully choosing its ground, many legal scholars are convinced that Section 5’s days are numbered. By those grim lights, the Justice Department’s quiescence isn’t saving the law—it’s just buying time. No liberal wants to let one of the defining laws of the civil rights movement die on their watch. Instead, they’re letting it waste away.