In a 5-4 decision, the Supreme Court ruled on the side of three corporations, reversing Montana's 1912 limit on corporate campaign spending.  Today's decision not only strengthens the 2010 Citizens United decision, but also affirms that it applies to the state of Montana. In defense of the corporations, lead attorney James Bopp stated:

"If Montana can ban core political speech because of Montana's unique characteristics, free speech will be seriously harmed. Speakers will be silenced because of corruption by others over a century ago."

The decision was split along ideological lines, with the 4 liberal justices dissenting, asking the court to reconsider the 2012 ruling because of the huge impact corporate finance has played in the electoral process since the January 2010 ruling.

Justice Breyer wrote the dissent, arguing that the political landscape in Montana gives the state a "compelling interest" in limiting independent expenditures by corporations:

Thus, Montana’s experience, like considerable experience elsewhere since the Court’s decision in Citizens United, casts grave doubt on the Court’s supposition that independent expenditures do not corrupt or appear to do so.

The Supreme Court's decision can be found here.