Is drawing a voting map that helps a political party illegal? Only in some states

Demonstrators opposed to partisan gerrymandering hold up representations of congressional districts from North Carolina (left) and Maryland (right) outside the U.S. Supreme Court in Washington, D.C., in 2019. (Carolyn Kaster/AP)

A recent unusual ruling by North Carolina's highest court has put a spotlight on the patchwork of state laws and court decisions that determine where maps of voting districts can be drawn to make elections less competitive and certain political parties more likely to win.

The practice is known as partisan gerrymandering, which, courts have found, both Republicans and Democrats have deployed when in control of redistricting.