HELENA — A second Montana judge has ruled there was corruption in the state’s 2010 Republican primary elections, with candidates pledging loyalty to a national anti-union group’s cause in exchange for thousands of dollars in illegal and unreported corporate campaign contributions.

State officials plan to use the two judicial rulings as evidence in their defense of Montana’s limits on how much political donors may contribute to a candidate’s campaign. A federal lawsuit seeking to strike down those limits is pending after the 9th U.S. Circuit Court of Appeals ruled last year that states must prove “quid pro quo corruption” — or the appearance of it — to justify capping contributions.

The U.S. Supreme Court’s 2010 Citizens United decision raised the bar for states to prove they have a legitimate interest in limiting campaign donations. Before the Supreme Court ruling, states only had to show the caps meant to curb the influence of big money on politicians. Now, they must show that the limits prevent an actual exchange of money for political favors, the 9th Circuit ruled.

Montana Commissioner of Political Practices Jonathan Motl said Wednesday that he believes two judges’ findings of corruption meets the new standard, but it will be up to a judge to decide.

“It is unprecedented and dramatic to have this degree of interference in elections that we saw in those 2010 primary elections,” Motl said. “If that isn’t quid pro quo corruption, I can’t imagine what is.”

District Judge James Reynolds ruled Tuesday that former Senate candidate Wesley Prouse accepted $9,421 in illegal contributions from secretive conservative groups funded by the National Right to Work Committee. Prouse, who lost a three-way 2010 primary election in Senate District 23, officially reported receiving only $260 in contributions and spending no money at all in his campaign.

The contributions came in the form of thousands of letters to voters signed with Prouse’s digitally scanned signature, plus letters and flyers prepared by the Right to Work-affiliated company Direct Mail and Communications Inc. The correspondence promoted Prouse and attacked John Esp, the candidate who won the 2010 primary.

Reynolds ruled the 7,017 letters sent to aid Prouse’s campaign amounted to at least $9,101 worth of illegal in-kind corporate contributions, and that Prouse also received $320 in cash contributions that he did not report. Prouse pledged to support the causes of Right to Work and its affiliates, which Reynolds said amounted to quid pro quo corruption.

“As the quid, Prouse received the appearance of a grass roots campaign created by Direct Mail for which he did not pay, report or disclose,” Reynolds wrote in the ruling. “As the quo, Prouse promised in return unswerving fealty to the corporations carrying out the direct-mail campaign on his behalf.”

The judge ordered Prouse to pay $59,066 in fines and barred him from running for office until the fines are paid and his campaign finance reports are changed to reflect the illegal contributions.

Prouse did not return a call for comment Wednesday, nor did he file a response to the civil complaint filed by Motl against him.

Reynolds’ ruling is similar to one made in August by District Judge Gregory Pinski that state House candidate Joel Boniek accepted more than $9,000 in contributions from the same Right to Work-affiliated groups. Boniek promised “complete opposition to the union bosses” in exchange for the campaign aid, Pinski wrote.

Prouse and Boniek are among nine Republican candidates from the 2010 election whom Motl alleges received illegal corporate contributions from the National Right to Work Committee and affiliates Direct Mail, Western Tradition Partnership and Taxpayers for Liberty.

Two candidates, including current state Rep. Mike Miller, R-Helmville, have settled out of court. A March 28 trial is scheduled for a fifth candidate, state Rep. Art Wittich, R-Bozeman.

Motl said he plans to use the Prouse and Boniek rulings, in addition to his findings against the other Republican candidates, in the lawsuit challenging the state’s contribution limits. U.S. District Judge Charles Lovell ruled in 2012 that the caps were too low to allow candidates to effectively campaign, but the 9th Circuit overturned his decision and ordered Lovell to re-examine the issue.

Tara Malloy, the deputy executive director of the Washington D.C.-based nonprofit Campaign Legal Center, said the state judges’ rulings may help in the defense of the state’s contribution limits. However, they don’t shed light on what would be an acceptable limit that would allow candidates to effectively campaign while preventing corruption, she said.

“It can’t hurt, but I don’t think it’s going to decide the case,” she said.