...Citizens United is arguing that the McCain-Feingold law is unconstitutional.
But the court has already ruled otherwise. In 2003, In McConnell v. FEC, the court ruled on a challenge to the McCain-Feingold Act brought by Sen. Mitch McConnell (R-Ky.), among others. The justices voted 5-4 to uphold the law. Normally, that would answer the question and put an end to the broader constitutional argument.
Since 2003, however, the composition of the court has changed. Justice O’Connor, who provided the critical fifth vote in favor of the law, has been replaced by Justice Samuel Alito, who’s made clear his skepticism of campaign finance restrictions. (Three of his colleagues — Justices Anthony Kennedy, Antonin Scalia and Clarence Thomas — have previously signed minority opinions advocating striking down campaign finance restrictions.) Chief Justice Roberts has also expressed concern about the campaign finance laws.
As a result, instead of deciding the case, the court announced in June that it would convene a special session to consider specifically whether it should reverse McConnell and another ruling from 1990, Austin v. Michigan Chamber of Commerce, which upheld a state’s right to limit direct corporate spending in elections. And the cases all build upon a long history of case law defining corporations and their role.
Just keep giving it away, people.
PS - According to this, The court's basic stance with respect to this issue is resting on some pretty thin, 100+ year old ice. But that hardly matters as long as you have a solid majority of uptighty righties on the bench. We'll see what happens. In the mean time here's some further reading on the topic: