PORTLAND, Maine (AP) — Maine is testing the legal limits of restrictions on so-called super PACs. Voters on Election Day approved a referendum limiting donations to political action committees that spend independently in candidate elections, setting the stage for a legal showdown. The law imposes a $5,000 limit for donations to super PACs and supporters fully expect a lawsuit that could go to the U.S. Supreme Court. The Supreme Court in 2010 allowed unlimited spending by super PACs. The Maine initiative doesn’t attempt to limit spending by super PACs but focuses instead on individual donations.