Deciding they didn't need to hear arguments, the justices today summarily reversed a Montana Supreme Court decision upholding the state's century-old ban. The state court had ruled the law's limits could stand for state elections even after Citizens United v. Federal Election Commission, the two-year-old Supreme Court ruling that let corporations and unions spend unlimited sums.
The court's unsigned opinion in the 5-4 ruling said the case asked whether Citizens United applied to a state law. "There can be no serious doubt that it does," the court said.
"Montana's arguments in support" of the lower court ruling "either were already rejected in Citizens United or fail to meaningfully distinguish that case," the opinion said.
The majority was identical to the 5-4 Citizens United decision, which altered the national political landscape and opened the way for campaign spending by outside groups to more than double from the level four years ago.
The latest action makes clear the court's five Republican appointees stand behind their conclusion that corporate campaign spending is entitled to broad protection under the First Amendment.
Critics of the Citizens United ruling had sought to leave room for spending bans at the state level, saying they guard against corruption.
"The states have a compelling interest in preventing domination of state and local elections by nonresident corporate interests," argued New York, joined by 21 other states and the District of Columbia, in a court filing backing Montana in the case.
"The decision today says that other states struggling to deal with corrupting political spending are essentially handcuffed," said Adam Skaggs, senior counsel of the Brennan Center's Democracy Program at the New York University School of Law. "The court has removed a promising tool for states."
Montana Attorney General Steve Bullock said in a statement that today "is a sad day for our democracy and for those of us who still want to believe that the United States Supreme Court is anything more than another political body."
The lawsuit over his state's corporate money ban "could have provided the court with the opportunity to revisit some of the fundamental fallacies underlying the Citizens United decision," said Mr. Bullock, a Democrat who is his party's gubernatorial nominee this year.
U.S. Senator Mitch McConnell, the Republican Senate minority leader from Kentucky, said in a statement the ruling is "another important victory for freedom of speech."
There has been "only minimal corporate involvement in the 2012 election cycle," Mr. McConnell wrote in the statement and in a brief filed in support of the group seeking to toss out Montana's corporate political spending ban.
Citing Federal Election Commission records, Mr. McConnell said "not one Fortune 100 company contributed a cent to any of the eight Republican super-PACs" as of the end of March.
Those committees are required to report donors; many nonprofit groups that also spend money in elections may keep their donors secret.