For what its worth, as I have argued here and in class since the Citizens United ruling that reduced spending restrictions for campaigns, the ruling wasn't going to matter. Lots of studies find that most corporations don't really spend that much to influence elections and weren't really constrained by the old laws (Ansolbehere, de Figuereido and Snyder ) and that money spent on elections really doesn't matter too much (Levitt).
Campaign spending was a whopping 13% higher in 2012 than in 2008, barely outpacing inflation, and by and large, we got pretty much the same electoral outcome as before too. Yay when social science works. Too bad neither pundits nod the media really care what social science says about elections. Even stats guru Nate Silver mostly ignores the literature to just do ad hoc statistics.