The U.S. Supreme Court will hear a lawsuit challenging how state legislative districts were drawn in Arizona in December.
The high court on Monday also has scheduled a voting rights case from Texas on the same day, Dec. 8.
Eleven Republican voters sued Arizona's Independent Redistricting Commission after new legislative maps were adopted in 2012. They claimed Republican voters were illegally shifted from some districts to make them more likely to elect Democrats to the state Legislature on the premise of complying with the federal Voting Rights Act.
A panel of federal judges found the commission did not violate the Constitution's equal-protection clause.
In the Texas case, justices will consider whether states must count only those who are eligible to vote, rather than the total population, when drawing districts for their legislatures.