U.S. Supreme Court justices on Monday wrestled for the second time over whether Republican legislators in Virginia drew electoral districts in the state in a way that unlawfully diluted the clout of black voters.

The high court heard arguments in an appeal by the Republican-led state House of Delegates in defense of 11 state House districts that a lower court ruled last year violated the rights of black voters to equal protection under the law under the U.S. Constitution's 14th Amendment.

The case involves gerrymandering, a practice involving the manipulation of electoral district boundaries to marginalize a certain set of voters and increase the influence of others.