Election law experts say the case is the best chance yet for the high court to put limits on what lawmakers may do to gain a partisan advantage in creating political district maps.
In the Wisconsin case, a federal court struck down the districts as unconstitutional in November, finding they were drawn to unfairly minimize the influence of Democratic voters.
The Supreme Court has never struck down districts because of unfair partisan advantage, although it has intervened frequently in disputes over race and redistricting over the past 50 years.
Similar lawsuits are pending in Maryland, where Democrats dominate, and North Carolina, where Republicans have a huge edge in the congressional delegation and the state legislature.
The court adopted an equation offered by the challengers that essentially measures and compares each party's wasted votes —those going to the winner in excess of what's needed for victory — in an election.