If Montanans don’t “own” their representatives in Congress and the state Legislature, someone else will, a University of Montana law professor and dark money opponent said Monday night.

Anthony Johnstone worked alongside then-attorney general Steve Bullock when Montana attempted to defend its longtime ban on corporate campaign contributions. The U.S. Supreme Court disagreed with the state, and the dark money floodgates opened. The financing's sources are never revealed, obscured behind dummy organizations and complex money trails. But the intent is clear: to "buy" politicians' votes.

That’s why it is incumbent upon every resident to get involved, Johnstone told the audience at a screening of the new Montana-centric documentary, “Dark Money.” Only widespread citizen involvement can counter the massive corporate spending on this, and other states', elections, he said.

“Get involved. Give money," he said. "It’s not dirty money if you support good candidates. You need to make sure that you own your candidates. If everyone is involved, then dark money doesn’t have a chance.”

A packed house filled the University Center Theater for the film’s second Montana showing, part of this year’s Big Sky Documentary Film Festival. The film debuted at the Sundance Film Festival.

Directed by Kimberly Reed, the film traces the long history of corporate influence over Montana politics – beginning with the Anaconda Co.’s domination of the Legislature, congressional representatives and the state’s major newspapers.

Montana voters rebelled, adopting the 1912 Corrupt Practices Act that prohibited corporations from contributing to political campaigns.

And that was the law until 2010, when – in its Citizens United decision – the U.S. Supreme Court said the government cannot restrict election spending by corporations, nonprofits or labor unions. To restrict those contributions, the court said, would violate the First Amendment’s free speech guarantee.

Of the states that prohibited corporate campaign contributions, only Montana defended its ban.

“The excesses of corporations, they’re in your face in Montana,” the film instructs. The evidence is as prevalent today as 100 years ago.

But ultimately, the state was not successful in its campaign against corporate contributions. By 2012, Montana voters were inundated by dark money attack ads and mailings. Simultaneously, the state's major newspapers began cutting their political and legislative coverage, laying off the most experienced journalists at the Capitol.

In the film, American Tradition Partnership attorney Jim Brown said he doesn’t believe there is too much money in politics.

“I think the Supreme Court got it right,” he said. Brown is among the attorneys who successfully argued in favor of unlimited corporate spending.

But now-Governor Bullock told the filmmakers that he believes the ATP wants to get rid of all regulation of election spending: the contribution limits, corporate restrictions, even truth in advertising laws. The attack continues, he warned.

“Dark money groups refuse to tell us who they are or what they do,” Bullock said. “We don’t know who funds these groups and probably never will.”

A corporation sends money to a dark money PAC, often via several intermediary companies. Then the dark money PAC purchases attack ads and mails disparaging postcards or pamphlets to voters – often just days before the election – attacking a candidate targeted for defeat.

When the desired candidate wins, they “owe” the corporation, usually having signed a pledge to win the PAC’s support.

Kalispell state Rep. Frank Garner said during a panel discussion following the screening that he was targeted by dark money groups because he refused to sign pledges supporting specific causes, corporations or special interest groups.

The dark money groups even hosted town hall meetings to attack him and other, similarly moderate Republicans who are willing to work with Democrats and find common ground, Garner said.

Rather than defeat Garner, the dark money PACs made an enemy dedicated to fighting the influence of dark money in Montana elections.

The audience heard, too, from attorney Gene Jarussi, who served as the state’s special prosecutor for 14 state legislators accused of illegally conspiring with the national Right to Work PAC to defeat their primary election opponents. All 14, he said, had signed a pledge to support the right to work, guns, tax cuts and to oppose abortion.

Three of the legislators were protected by the statute of limitations and continue to serve in the Montana Legislature, Jarussi said. The remaining either settled with the state out of court, lost in court or await trial.

“This is our state,” he said. “Make sure you know where your candidate stands on our commissioner of political practices. Make sure he or she supports that office, because it is under attack.”

Montana is the only state that has a post overseeing the investigation and prosecution of campaign violations. Dark money groups “can’t wait to dismantle it,” said Jarussi.

And finally, he advised, “become a candidate yourself.”

“If you have the ability, consider running. If you can do that, it is one heck of a contribution.”