An unprecedented amount of corporate cash is flooding into the Republican presidential race, fueling a barrage of attack ads that bloodied several candidates before Barack Obama could even step into the ring.

A 2010 U.S. Supreme Court ruling that granted corporations and labor unions the freedom to spend unlimited amounts of money on campaign ads has opened the door to so-called super-PACs, political action committees that can raise as much money as they want as long as they don’t directly coordinate their attack ads with the campaign they’re supporting.