More than two billion dollars. That's how much money was spent in the 2012 presidential campaign--the most expensive campaign in history. Each party raised and spent more than one billion dollars as the traditional boundaries of campaign financing were ignored. Both parties could do so because they were playing in a game with new rules--rules that largely developed after the 2010 Supreme Court ruling known as Citizens United. That case removed many restrictions on donation limits, particularly for corporations and unions. The result was the development of a new set of political players called...