The U.S. Supreme Court has issued a summary reversal of the Montana Supreme Court's decision to uphold a state law that prohibited corporate spending in state elections. The U.S. court said the question in this case was whether the Citizens United decision, which established that corporate spending in elections is permitted as a matter of free speech, applied to the Montana state law. "There can be no serious doubt that it does," the court wrote.

The summary reversal was not an unexpected outcome. As Adam Liptak of the New...