In a 5-4 ruling, the Supreme Court has refused to expand the protections for minorities under the federal voting rights law, a decision that may affect the redrawing of legislative boundaries after the 2010 Census. The court’s conservative majority ruled only electoral districts with majority of blacks or other minorities are to be protected by a provision of the Voting Rights Act. Civil rights groups said the ruling could result in more districts with minorities constituting less than half the population, diluting their voting strength.