PHOENIX - Arizona's 30 legislative districts need to be redrawn before the 2014 election, an attorney for Republican interests contends, citing the U.S. Supreme Court's recent ruling that voided a key section of the Voting Rights Act.

In legal papers filed in federal court late Friday, attorney David Cantelme said the Independent Redistricting Commission's data show that it overpopulated some of the districts and underpopulated others.

he result was to politically disadvantage Republican candidates, he said.

Cantelme also pointed out to the three-judge panel that the commission's key legal argument for why it made those decisions was that it needed to comply with the federal Voting Rights Act.

Commissioners wanted to ensure that the map it drew was "precleared" by the U.S. Justice Department and didn't dilute the voting strength of minorities.

But the high court last month overturned a provision of that law that created a formula to identify which states and counties have a history of discrimination and must submit any changes in voting laws to be precleared. That list included nine states, including Arizona, and parts of several others.

The justices said the formula, parts of which date back to 1965, is no longer valid.

With the formula now void, no state or county is subject to preclearance. The court ruling effectively means the commission had no legal right to skew the maps to meet Department of Justice concerns, Cantelme said.

Attorneys for the commission give their response to Cantelme's argument next month.

But attorney Joe Kanefield said the Supreme Court ruling is legally irrelevant. He said the commission, in drawing the maps in 2011, had to rely on the law as it stood at the time.

The Supreme Court ruling came a year after Cantelme first sued.

The outcome of this legal battle could determine the makeup of the Legislature for the balance of the decade.

If the trial court agrees with Cantelme, the judges could order the commission to redraw the maps.

Voters created the commission in 2000 to draw lines for congressional and legislative districts, a task that previously was left to state lawmakers.

The constitutional amendment requires them to draw lines that create districts of equal population. On paper, that should mean 30 legislative districts, each with about 213,000 people.

But the commissioners also are charged with other issues, including protecting communities of interest, creating politically competitive districts and complying with the Voting Rights Act.

The final maps had districts in size from 203,026 to 220,157 people. Commissioners said those adjustments ensured there would be no objections from the Justice Department affecting minority voting strength.

Cantelme contends the goal was to create as many districts as possible where Democrats had a chance of winning by purposely moving Republican strongholds into adjacent - and already Republican - districts.

He said that happened because commission Chairwoman Colleen Mathis, while a registered independent, routinely sided with the two Democrats on the panel against the two Republicans.

Before the latest redistricting, Republicans controlled 21 of the 30 seats in the Senate and had 40 of the 60 House slots. After redistricting the GOP edge was reduced to 17-13 in the Senate and 36-24 in the House.

But there were other factors, including that 2012 was a presidential election year. And while Barack Obama did not carry Arizona, his presence on the ticket may have brought out more Democrat voters.

If the judges intend to order the legislative maps redrawn, they need to act quickly: Incumbents and challengers already have been forming campaign committees for the 2014 race.