WASHINGTON — The U.S. Supreme Court today upheld Arizona congressional districts drawn by an independent commission and rejected a constitutional challenge from Republican lawmakers.The 5-4 outcome preserves efforts in 13 states to limit partisan influence in redistricting. Most notably, California uses an independent commission to draw electoral boundaries for its largest-in-the-nation congressional delegation.The Arizona case stemmed from voter approval of an independent commission in 2000. The legislature’s …