Jan 10 (Reuters) - A day after the Supreme Court heard arguments in a Texas redistricting battle, another redistricting case with potential national implications takes center stage, this time in Florida.

On Tuesday, the U.S. Court of Appeals for the 11th Circuit will hear a challenge in a racially-charged lawsuit over an amendment to Florida's constitution. Lawmakers have sued to try to block the amendment -- passed by voter ballot in 2010 -- which they say violates the U.S. Constitution because it strips the legislature of its right to regulate elections.

An African-American Democrat and a Hispanic Republican, joined by Florida's House of Representatives, sued Florida in 2010, arguing that the so-called Fair Districts amendment dilutes the voting power of minorities. They also say it violates the Elections Clause of the Constitution, which gives state legislatures the power to regulate the time, place and manner of congressional elections.

The Florida issues echo, but differ, from those in the Texas fight, which the Supreme Court justices will decide by the end of this term.

In Texas, the dispute involves challenges under the 1965 Voting Rights Act, particularly a requirement that states with a history of discrimination obtain court approval for redistricting plans. The case centers on maps drawn up by a San Antonio federal court, which Republican state officials say went too far and should have deferred to maps approved by the Republican-controlled state legislature.

A number of states around the country, including California and Arizona, have established commissions that limit the state legislatures' influence over the redistricting process. A win for the challengers in the Florida case could be a blow for that movement.

As often happens after the once-a-decade census, there have been dozens of challenges to new congressional maps. In the wake of the 2010 census, 115 redistricting challenges have been filed in state and federal courts around the country. That is down from 149 filed after the 2000 census, but more challenges are likely to be filed, according Justin Levitt, a professor at Loyola Law School, who tracks redistricting cases. "This is only the beginning," Levitt said.

The Florida fight grows out of longstanding political and racial tensions in the state. Before 1992, Florida had not elected a single African-American representative since the Reconstruction Era. But in that year, Republicans joined forces with black and Hispanic lawmakers to push for maps that consolidated minority voters in a handful of districts. The strategy helped minority candidates from those districts, but also made the surrounding districts more Republican, causing the Democratic Party to lose its longstanding control of the state legislature.

Corrine Brown, an African-American Democrat who filed the suit, was one beneficiary. She was elected as U.S. Representative for Florida's Third Congressional District in 1993, thanks to the percentage of black voters in the oddly-shaped district, which zigzags from Jacksonville south to Orlando. That year, two other districts also elected African-Americans to Congress.

Brown, who filed the suit with fellow Representative Mario Diaz-Balart, said that the Fair Districts amendment threatens to reverse the gains in minority representation by fragmenting black and Latino voters.

The amendment requires new districts to be compact, adopting the existing borders of cities and counties.

Proponents of the amendment "believe that by eliminating minority districts, they can pick up some white Democrat congressional seats," Diaz-Balart said in an interview with Reuters. He said his own position is not at risk, but that the amendment could jeopardize at least two African-American seats in Congress.

The challengers' main ammunition is a 1995 decision in U.S. Term Limits Inc v. Thornton in which the Supreme Court ruled that states cannot use a constitutional amendment to impose term limits on members of the U.S. Congress stricter than those specified in the U.S. Constitution. Therefore, states cannot limit a legislature's redistricting powers under the Elections Clause, the suit claims.

Opponents accuse Brown, who declined to comment on the case, and Diaz-Balart of acting out of self-interest.

"Republicans have rallied behind Brown because they are in a position of power, and what she's trying to protect is their ability to stay in power," said Leon Russell, vice chairman of the National Association for the Advancement of Colored People, which has intervened in the suit on behalf of Florida. Russell said some districts now contain a higher percentage of minority voters than needed to elect a candidate of their choice, solidifying Republican control.

The state is relying on two Supreme Court cases, which it says support the right of voters to limit the legislature's redistricting powers. In the 1916 case Ohio ex rel Davis v. Hildebrant, the Supreme Court allowed Ohio citizens through a voter referendum to veto a congressional redistricting plan passed by the state legislature. In Smiley v. Holm in 1932, the high court found the Minnesota governor's veto power could trump the legislature's plan.

"I think the complaint is just frivolous," said Laughlin McDonald, a lawyer for the ACLU defending the amendment. He said the Miami trial judge agreed, rejecting the challenge last September.

If the 11th Circuit were to find the amendment unconstitutional, states that have taken steps to regulate redistricting could be affected, McDonald said. The independent commissions that states including California and Arizona have established to make redistricting less partisan could be called into question.

The plaintiffs' lawyer, Stephen Cody, pointed to California's commission as one of the most extreme, taking redistricting out of the hands of the legislature. But he said he had not examined the details to know whether it's unconstitutional.

The Florida case is Corrine Brown et al v. State of Florida et al, U.S. Court of Appeals for the 11th Circuit, No. 11-14554.

For Brown et al: Gregory Garre of Latham & Watkins.

For Florida et al: Daniel Nordby of the Florida Department of State; Michael DeSanctis of Jenner & Block.

(Reporting by Terry Baynes)

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