The Supreme Court revived a fight over Georgia legislative boundaries yesterday, agreeing to clarify how line-drawing must be done to protect the voting rights of minorities.

The justices will consider reinstating legislative district lines that a lower court rejected last spring. That three-judge panel said lawmakers had wrongly reduced minority voting strength in several Georgia Senate districts.

States must redraw boundaries every 10 years to reflect population changes. The Georgia case gives the Supreme Court a chance to clarify how states can redraw districts with heavy black populations without violating the federal Voting Rights Act.

The challenged redistricting plan, drawn by the Democratic-controlled legislature, shifted black voters from safe Democratic districts into adjacent districts as part of a strategy to oust Republicans.

After losing in the lower court, Georgia lawmakers redrew the state Senate boundaries, and elections were held in November in the approved districts.

Those elections went badly for Democrats. The state elected its first Republican governor in 130 years, and Democrats lost state Senate seats. Republicans took control of the state Senate when four Democrats switched parties.

The Bush administration had urged the justices to stay out of the case, which would have left the new map in place. The case, Georgia v. Ashcroft, No. 02-182, will be argued this spring.

The court also said it would consider whether Iowa can impose higher taxes on slot machine profits than on the profits of riverboat casinos. The Iowa Supreme Court had ruled that it was unconstitutional to put higher taxes on companies that operate slot machines at dog and horse tracks. The state will have to refund $100 million in taxes if it loses the appeal. The case is Fitzgerald v. Racing Association of Central Iowa, No. 02-695.

The justices also agreed to hear an energy regulation case that asks what costs utility companies can pass on to consumers. At issue is how a state can control rates charged by companies that have operations in more than one state. The case is Entergy Louisiana v. Louisiana Public Service Commission, No. 02-299.