With just three weeks left before the upcoming midterm elections, a group called "Kansans for Justice" surfaced with the aim of persuading voters to oust two of their state Supreme Court justices.

"Your Kansas Supreme Court justices are using their political beliefs to rule against sound court cases," the group's website said. "On November 4th, vote No and remove Kansas Supreme Court Justices Eric Rosen and Lee Johnson from the bench."

Kansas Supreme Court justices are appointed by the governor, but at the end of each justice's six-year term, voters decide whether to retain the judge or allow the governor to pick a replacement.

The unexpected emergence of Kansans for Justice in what have historically been uncontested retention races has exposed a loophole in the state's campaign finance rules: Even though the group has all the hallmarks of a political committee – it is soliciting contributions, plans to send mailers, and has an explicit electoral goal – it's not required to report anything about its leadership, donors or spending.

The disclosure requirements imposed on groups that try to influence other types of races don't apply because Supreme Court justices are not included in Kansas' legal definition of "state officers" – an omission that shocked even the attorney at the state agency that oversees campaign finance.

No one appears to track the rules around these elections but a ProPublica review found that at least one other state has a similar gap in campaign finance regulation for these increasingly politicized races. Experts called the lack of transparency worrisome, leaving voters unable to see who's trying to influence retention elections and the system blind to the potential conflicts of interest that could arise if backers of such efforts come before the courts they helped remake.

"It's a particularly egregious form of dark money," said Alicia Bannon, an attorney with the Brennan Center for Justice at the New York University School of Law, who has been critical of special interest influence in judicial races. "Not only do you not know who's behind the spending, you don't even have information about what spending is taking place ... there can be groups that are having quite a significant impact on a state's race without any kind of public scrutiny."

In an early interview, a spokeswoman for Kansans for Justice described the group as a nonpartisan, grassroots effort.

"Our goal is really to reach Kansas voters, help them understand what the Kansas Supreme Court is doing," Amy James said. "We obviously feel a change is needed."

The group did not respond to a request for information about their donors and spending.

One of the group's supporters said its anti-retention push shouldn't be subject to disclosure rules because it's not a political campaign in support of particular candidates, but rather against the two incumbents.

This particular retention vote, however, could have distinctly political consequences. The two justices targeted by Kansans for Justice were appointed by a Democrat, former Gov. Kathleen Sebelius. If they're voted out, their replacements could be chosen from a pool submitted to Republican Gov. Sam Brownback, who's embroiled in a contentious fight for re-election himself. Brownback has made eliminating "liberal" justices one of his central campaign promises. Depending on the election results, the court's balance could shift from 4-3 in favor of Democratic appointees to 5-2 in favor of Republican appointees.

Across the country, state Supreme Court races have become increasingly politicized, a trend that supporters say helps hold judges accountable for legislating from the bench and critics call a threat to judicial independence.

According to the Brennan Center, outside groups and parties spent upwards of $24 million on Supreme Court contests during the 2012 election cycle, about twice as much as the two previous cycles combined. Unlike megabuck federal elections, as little as a few hundred thousand dollars can swing these races, giving donors more bang for the buck.

Most of the attention has focused on states where voters elect justices, not on the 20 states where governors appoint them and voters only get to decide whether they're retained. But in these states, too, political activity around judicial contests has ratcheted upward.

During the last cycle, justices in Florida faced an expensive challenge from the state Republican Party and Americans for Prosperity, a group supported by billionaire brothers David and Charles Koch. In that race, all three justices were ultimately retained, despite ads blasting them for a decision to block a proposition aimed at blunting Obamacare. Even some Republicans called the anti-retention campaign a threat to judicial independence.

In 2010, three justices up for retention in Iowa were booted from office after a ruling that legalized same sex marriage. The groups that funded the anti-retention movement, which included the National Organization for Marriage and the American Family Association, significantly outspent their opposition.

The disclosure rules for outside groups active in retention elections vary considerably from state to state, a ProPublica review found.

In states such as California and Tennessee, groups campaigning for or against retention have to register and report on their fundraising and spending just like any other political committees.

But at least one other state, Utah, appears to take the same approach as Kansas. In an interview, Utah's deputy director of elections initially said groups campaigning against retaining a justice would have to register as political committees. But upon reviewing the election code, he found that justices aren't included in the state's definition of "public office."

"It's just surprising," said Justin Lee, the deputy director. "Anything else on the ballot, whether an issue or a proposition or any candidates, when you're spending money for or against it, that has to be disclosed and registered."

In Kansas, the gap in campaign-finance rules was discovered when Brett Berry, the lawyer for the state's Governmental Ethics Commission, received an inquiry from a man who said he was calling on behalf of the friends and relatives of Wichita Massacre victims.

In this 2000 incident, one of the most notorious crimes in the state's history, two brothers went on a week-long killing spree. Earlier this year, the Kansas Supreme Court tentatively vacated the brothers' death sentences because of problems with the jury instructions in their trial.

The man who called Berry asked him what the reporting obligations would be for a group expressly advocating against the retention of a Supreme Court justice.

Berry thought the answer was obvious.

"I told him they'd have to register as a PAC," Berry said, referring to political action committees, which in Kansas are required to register and reveal their donors and expenditures.

But then he dug further and found an obscure 2010 ethics opinion that concluded Kansas' campaign finance law doesn't apply to judicial retention elections.

"And it dawned on me," Berry recalled. "I called him back and told him 'You don't have to register as a PAC and you're not subject to the reporting requirements ... Campaign finance doesn't apply.'"

Berry said he doesn't understand why state law allows this type of political spending to go completely unchecked.

"It just seems like it's something we should be regulating because we regulate state and local offices," he said. "You think of a Supreme Court justice. They're on the ballot. That's a state office."

Days after Berry told the caller no disclosure was required, Kansans for Justice was launched. The group has gotten a flurry of local press since unveiling its campaign against Rosen and Johnson. It takes donations on its website, and plans to send out political mailers urging Kansans to oust the two "activist" judges.

The man who called on behalf of the group, Berry said, was David Gittrich – a well-known anti-abortion activist. In the past, Gittrich has been a vocal critic of activist judges on the state Supreme Court, and his organization, Kansans for Life, has unsuccessfully encouraged voters to oust such jurists.

Asked by ProPublica about his relationship with Kansans for Justice, Gittrich said he had read about them in the newspaper. "That's it," he said. "Got about as close a relationship with you as I do with them, closer with you because I've talked to you."

Gittrich acknowledged he had called Berry on the group's behalf, but said he was doing a favor for a friend associated with the group. He would not identify the friend.

Kansans for Justice did not respond to questions about what relationship the group has, if any, with Gittrich.

Bannon, the critic of special interest influence in judicial races, said states that don't require disclosure for retention campaign spending need to update their laws.

"It's deeply troubling," she said. "The increased politicization of judicial election and retention is a new political phenomenon. States haven't kept up with this new reality."