While there is a slim possibility of a challenge in court, the likelihood is that Louisiana’s new lines for districts of members of Congress are set for the 2012 election.

After the 2010 census, lines for legislative districts and other posts were redrawn to reflect at least generally the principle of equal population. The plan for Congress was the most contentious of this year’s special session of the Legislature, which is required to produce the new maps.

A main reason for the disputes about the congressional lines: Louisiana lost a seat in the U.S. House of Representatives. As a result, two Republican incumbents in the seven-member delegation will be in the same district in 2012, should both seek re-election. They are U.S. Reps. Charles Boustany, of Lafayette, and Jeff Landry, of New Iberia.

The lines for Congress also were contentious in part because Democrats sought to draw at least one “horizontal” district in north Louisiana that might have given a black candidate a better chance of winning the seat.

If there is a legal challenge to the new lines, it would be because of that rancorous debate about the Legislature selecting instead two “vertical” districts based on Shreveport and Monroe areas and reaching south to provide a sufficient population to justify each seat.

Louisiana is one of the states whose districts must be cleared in advance with the U.S. Justice Department because of a history of racial discrimination in voting here.

The department cleared the new House districts recently.

While that doesn’t mean someone cannot file suit under the Voting Rights Act, as the Justice Department noted, it is much more difficult to overturn the lines through the courts.

Because members of Congress don’t come up for election until next year, there also was some argument that the map didn’t have to be drawn during the special session which tackled other districts, including those for members of the Legislature. We believe it was best to get all of that done at one time, as the lawmakers did.

All that said, and pre-clearance from the Justice Department having been achieved, the map is still something of a mess. The two districts drawn to protect the political interests of incumbent Republicans Rodney Alexander, of Quitman, and John Fleming, of Minden, sprawl over the map. Alexander’s new district goes from the Arkansas line to St. Landry Parish, and also across the Baton Rouge area to Washington Parish.

Baton Rouge’s region is split into several districts. Part is represented by Alexander, although most of the area parishes and most of the population continue to be represented by U.S. Rep. Bill Cassidy, R-Baton Rouge.

But his district now goes south as far as Terrebonne and Lafourche parishes and others formerly in Landry’s district.

Many black voters in the region are now in a district in New Orleans. The rules of the game under the Voting Rights Act essentially require that an overwhelmingly black district be drawn, and that was the simplest way to create one with sufficient population.

For Democrats, this is one of the unintended consequences of the Voting Rights Act: Their black voter base is sequestered in districts so that other districts get “whiter.”

While that doesn’t entirely explain the decline of the Democratic Party in Louisiana in recent years, it is a contributing factor — and one that few are willing to change, as black incumbents obviously don’t wish to change a system favoring their interests.

The new districts, while passing Justice Department clearance, provide safer seats for GOP incumbents. We doubt we’ll hear them complaining about long drives around their tailored districts.