PHOENIX — The nation’s high court will hear arguments in less than two months on the legality of the state’s 30 legislative districts, setting the stage for a ruling that could realign political lines for the 2016 election.

Attorney Mark Hearne, representing Republicans challenging the current districts, said Monday the Dec. 8 hearing could portend a quick ruling by the Supreme Court. And he said if the justices side with him — and against the Independent Redistricting Commission — there is probably no excuse to keep the current lines in place for the next election.

Mary O’Grady, who represents the commission, said she’s not sure the case can move that quickly.

But if the case goes against the commission, it could send shock waves through the system, whether next year or in 2018.

Hearne contends the commission created districts that do not have equal population, which he said is a violation of constitutional “one man, one vote” requirements. If the court agrees, Hearne said it would mean the commission has to go back and try again, this time making the numbers come out even.

That, however, would be no small feat: Hearne said 2 million people — close to a third of the state’s population — would have to be moved to different districts to meet equal-population requirements.

Potentially more significant, it likely would mean some incumbents find they no longer live in the districts from which they were elected. That would mean either moving or deciding to run in their new districts — districts that may already have incumbents.

The issue before the U.S. Supreme Court is twofold.

One is the contention that commission members broke the law when they intentionally “packed” non-Hispanic Republicans into some districts.

Using 2010 census figures, each legislative district should have an “ideal” population of about 213,000. But the commission, by its own admission, created districts ranging from 203,026 to 220,157.

The second is Hearne’s argument that the disparities were created for political purposes. He said the remaining districts — the one from which the Republicans were moved — had a higher proportion of Democrats, giving candidates from that party a better chance of getting elected.

District 8 is a prime example.

It stretches from Casa Grande through Florence and the San Tan Valley, all the way to Globe in one corner and Oracle in the other. It also is below that “ideal” population.

Yet it turned out the district is far from a Democrat lock. While voters elected Democrat Barbara McGuire to the state Senate, the two House seats are occupied by Republicans Frank Pratt and T.J. Shope.

A three-judge panel hearing the case in Phoenix agreed with challengers about the population differences. And they said the resulting districts benefited Democrats.

But the majority accepted arguments by commission attorneys that was it done in hopes of ensuring that the U.S. Department of Justice, which at the time had to “pre-clear” redistricting maps, would find them in compliance with the federal Voting Rights Act and its mandate to not dilute minority voting strength.

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Hearne acknowledged that if the justices find flaws in the Arizona map, crafting new lines is not a simple — or even quick — matter, with multiple steps to the procedures the commission must follow.

“The process in Arizona is they draw the grid maps,” he said, sort of a rough first step. Then they make adjustments to get a draft map.

And there are public meetings and hearings throughout the process.

Even if the justices side with challengers, O’Grady said there is one other factor that could make it difficult to get new maps for the 2016 race.

“The court would, in its decision, identify what the trial court did wrong,” she said. O’Grady said that would then require the three-judge panel to reconvene, analyze the Supreme Court ruling, and only then direct the commission to make changes.

“So there are multiple steps,” O’Grady said, all of which would make affecting the 2016 election less likely.

There’s one other factor that could complicate matters.

The justices are hearing another case the same day that deals with the question of whether the “one man, one vote” requirement applies to the entire population, as is the practice in Arizona, or only to those who can vote.

Challengers in that case contend that large populations of ineligible voters in some districts, including prisoners and people who are not U.S. citizens, effectively gives each of the eligible voters in those districts more political power than those living in districts with a higher population of voters.

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