In 1964 the U.S. Supreme Court ruled in Wesberry v Sanders that districts need to be drawn to be of equal population “as nearly as is practicable.” The idea was that an individual’s vote should be counted — and represented — equally in the House of Representatives.
Justice John Marshall Harlan concluded in the court’s majority opinion:
“While it may not be possible to draw congressional districts with mathematical precision, that is no excuse for ignoring our Constitution’s plain objective of making equal representation for equal numbers of people the fundamental goal for the House of Representatives. That is the high standard of justice and common sense which the Founders set for us.”
State legislatures are responsible redistricting in 37 states. In 4 states, the task falls to independent commissions. In 2 states, commissions composed of politicians draw state legislative district maps. The remaining 7 states contain one congressional district each, rendering congressional redistricting unnecessary.
Nothing in that decision authorizes a court, either state or Federal to draw the map.