The Supreme Court is taking up a racially and politically charged case from Louisiana that tests a landmark civil rights law enacted 60 years ago to prevent racial discrimination in voting.

The Supreme Court may help the GOP keep control of the House of Representatives next year by clearing the way for Republican-led states to redraw election districts now held by Black Democrats.

If the high court overturns the act's Section 2 — a provision that bans racial discrimination in voting — GOP-controlled states could redraw at least 19 more voting districts for the House of Represe...