The Freedom from Religion Foundation filed a lawsuit with the U.S. District Court against the Internal Revenue Service Wednesday over the IRS’s alleged failure to enforce the electioneering restrictions against churches and religious organizations.

The FFRF, a Madison-based group, filed the lawsuit in the Western District of Wisconsin. So far, the largest challenges to the lawsuit have been proving that the group has received unequal treatment under the law and that there is precedent for the case.

“There is precedent for the IRS withdrawing a charitable religious organization’s tax-preferred status due to violating the so-called electioneering prohibition of the tax laws,” said Scott Idleman, a Marquette law professor who specializes in constitutional law as well as law and religion.

Those cases are very rare, however, and are a result of IRS action on the religious organization, not the result of an outside group, such as the FFRF, making the IRS initiate some type of enforcement action.

Branch Ministries v. Rossotti, in which the religious organization Branch Ministries sued the IRS, occurred after the IRS revoked Branch Ministries’ tax-exempt status as a church for placing full-page advertisements in newspapers before the 1992 presidential election.

“Because the Church has failed to establish that it was singled out for prosecution from among others who were similarly situated, we need not examine whether the IRS was improperly motivated in undertaking this prosecution,” the brief from the D.C. Circuit Court of Appeals said. “We find that the revocation of the Church’s tax-exempt status neither violated the Constitution nor exceeded the IRS’s statutory authority.”

Three of the instances that the FFRF has most strongly protested were actions and letters from Catholic bishops to their constituents.

For instance, the Most Rev. David L. Ricken, the archbishop of Green Bay, argued against voting for individuals who go against certain tenets of Catholicism in a letter inserted in all Green Bay parish bulletins.

“Some candidates and one party have even chosen some of these as their party’s or their personal political platform,” Ricken wrote in the letter. “To vote for someone in favor of these positions means that you could be morally ‘complicit’ with these choices which are intrinsically evil. This could put your own soul in jeopardy.”

Other examples include the Rev. Daniel Jenky, bishop of the Diocese of Peoria, Ill., who publicly argued against the Affordable Care Act, and the Rev. Robert Molino, bishop of the Diocese of Madison, who wrote out guidelines for forming a Catholic conscience in certain areas that are non-negotiable.

Despite the fact that Ricken did not endorse one individual or party, the FFRF has argued that this political activism goes against IRS tax code restrictions on a religious organization.

“Under the Internal Revenue Code, all IRC section 501(c)(3) organizations, including churches and religious organizations, are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign on behalf of (or in opposition to) any candidate for elective public office,” the IRS Tax Guide for Churches and Religious Organizations states.

Idleman said he is unsure, however, how the lawsuit will continue.

“Parties in federal court suits need standing, and I can’t assess whether the FFRF can show that it has standing to sue,” he said.