Montana has engaged in a long, slow dance between corporations and politicians through much of its history. The free-spending audacity of the copper kings during the early 20th century — when the Anaconda Co. controlled judges, legislators and newspapers, and business magnate W.A. Clark bought himself a seat in the U.S. Senate — are the stuff of Western lore.

Fighting back, Montana voters in 1912 passed an initiative barring direct corporate contributions to political candidates and parties, a law that like those in many states was undone by the U.S. Supreme Court's controversial decision in 2010 that gave corporations the same First Amendment rights as citizens to spend their way into political debates.

But the Montana Supreme Court last week issued a forceful rebuke of the decision that has opened the door to game-changing, free-spending corporate contributions in the current election season. In a new opinion that draws on decades of Montana's coal-mining and copper-mining history, the court upheld the state's 1912-era corporate contribution limits, concluding, "The corporate power that can be exerted with unlimited political spending is still a vital interest to the people of Montana."

The decision applies only to state elections. But, if appealed as expected, the case could provide the long-awaited vehicle critics have sought for the U.S. Supreme Court to revisit the issue of corporate contributions. The Citizens United case in 2010 struck down federal prohibitions on such donations, called into deep question laws such as Montana's in 24 states and opened the door to large, often anonymous corporate expenditures in campaigns across the country — including the hotly contested U.S. Senate campaign in Montana.

In a 5-2 opinion, the state justices concluded Montana's long history of well-funded natural-resource extractors, small population and historically inexpensive political campaigns allows it to demonstrate the kind of compelling government interest in regulating corporate financial muscle that the court said is allowable even under the U.S. Supreme Court's broad First Amendment guarantees for corporations.

Indeed, even one justice who dissented — arguing the U.S. Supreme Court left no room for states to exempt themselves — argued forcefully against the broad corporate latitude encompassed in the Citizens United decision.

"Corporations are not persons. Human beings are persons, and it is an affront to the inviolable dignity of our species that courts have created a legal fiction which forces people — human beings — to share fundamental, natural rights with soulless creatures of government," Justice James Nelson wrote in his reluctant dissent. "Worse still, while corporations and human beings share many of the same rights under the law, they clearly are not bound equally to the same codes of good conduct, decency and morality, and they are not held equally accountable for their sins. Indeed, it is truly ironic that the death penalty and hell are reserved only to natural persons."

The Montana case centered on a constitutional challenge by American Tradition Partnership, a group that has funneled large amounts of money in lobbying efforts to battle environmental regulations.

In a fundraising appeal cited by the court, the group's website boasts of the anonymity it offers corporate donors.

"No politician, no bureaucrat, and no radical environmentalist will ever know you helped make this program possible," that appeal states.

Montana Attorney General Steve Bullock, a Democratic gubernatorial candidate who argued the case, said the state demonstrated that business in Montana easily can contribute through political-action committees with a minimum of regulatory hurdles.

At the same time, he said in an interview, the potential impact of unlimited corporate spending is disproportionately large in a state like Montana. "It doesn't take a heck of a lot of money to wind up influencing a state election where our average legislator ends up winning I think on $17,000," he said.

"Montana has a long history of corporate influence in elections," he added, "and ultimately the citizens are saying no, that's not how we want to run our elections."

John Bonifaz of Free Speech for People, a national group that is pushing for a constitutional amendment to overturn Citizens United, called the Montana decision an "enormously significant ruling" that, if appealed as expected, could result in a new U.S. Supreme Court review of how state campaign laws are affected by the Citizens United decision.

"Even if the Supreme Court lets (the Montana decision) stand," he said, "it would effectively open the door for every other state in the union to implement bans on corporate money in elections or to let stand their existing laws that have banned corporate money in state elections on the grounds that the Montana Supreme Court has used, which are that there are distinguishing constitutional interests that justify such laws."