The U.S. Supreme Court reaffirmed its 2010 Citizens United decision on Monday, summarily reversing a decision by Montana's Supreme Court that would have allowed the state to limit political spending by corporations.

In a divisive 5 to 4 vote, the court reversed the Montana ruling upholding a century-old ban on independent political spending by corporations, a drawback for reformers who hoped the Montana case would be the first step to chipping away at Citizens United in order to stem the increasing amount of special interest money in state and federal elections.

A summary reversal means the court made the decision without a full briefing or oral arguments. In the dissent, written by Justice Stephen Breyer, the dissenters explain they were not granting review of the case because there is no chance the majority will reconsider their stance on Citizens United.

The case, known as American Trader Partnership Inc. v. Bullock, emerged when Montana continued to enforce its longstanding ban after the nation's high court ruled in Citizens United that bans on independent political spending by corporations was unconstitutional. While 23 other states with similar regulations stopped enforcing the laws in place, Montana continued to enforce its Corrupt Practices Act, leading the conservative nonprofit American Tradition Partnership (ATP) to challenge the law by arguing it violated companies' First Amendment right to free speech as guaranteed by Citizens United.

After the law was upheld by the state supreme court, the ATP petitioned the U.S. Supreme Court to hear the case on appeal.

In their one-page decision, the five-justice majority said the Montana case offered arguments that were already considered -- and rejected -- in the Citizens United decision.

The question presented in this case is whether the holding of Citizens United applies to the Montana state law. There can be no serious doubt that it does... Montana's arguments in support of the judgment below either were already rejected in Citizens United or fail to meaningfully distinguish that case, reads the opinion.

However, in the dissent, Breyer argued that the history surrounding the Montana law -- developed in response to the influence and corruption corporate expenditures had on state politics during the turn of the 20th century -- demonstrates the state had a compelling interest in limiting independent expenditures by corporations.

Even if I were to accept Citizens United, the Court's legal conclusion should not bar the Montana Supreme Court's finding, made on the record before it, that independent expenditures by corporations did in fact lead to corruption or the appearance of corruption in Montana, reads the dissent. Given the history and political landscape in Montana, that court concluded that the State had 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.

Breyer was joined by Justices Sonya Sotomayor, Ruth Bader Ginsburg and Elana Kagan in the dissenting opinion.

Following the Supreme Court's decision, supporters of campaign reform said the ruling was demonstrative of the hold Citizens United has over both the justices and the nation's political system.

The Supreme Court continues to deny reality when it comes to assessing the impact of independent spending on elections. The court is not going to overturn Citizens United, at least in the near term. It thus falls on the people to overturn the court, through a constitutional amendment, said Robert Weissman, the president of the non-profit Public Citizen, said in a statement.

U.S. Sen. Bernie Sanders, I-Vt., an outspoken opponent of Citizens United, also called for a constitutional amendment to reverse the campaign finance law.

In recent weeks, multi-billionaires such as the Koch brothers and Sheldon Adelson have made it clear that, as a result of the Citizens United decision, they intended to spend hundreds of millions of dollars to buy this election for candidates that support the super-wealthy, Sanders said in a statement. This is not democracy. This is plutocracy. And that is why we must overturn Citizens United if we are serious about maintaining the foundations of American democracy.

Of course, the ATP believes the Supreme Court's decision already has upheld American Democratic values, declaring in a statement that the summary reversal is a rejection of indefensible attacks on Montanan's God-given right of free political speech.

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