A Roman Catholic priest’s sexual relationship with an adult parishioner he is advising on spiritual matters is ­condemned by the church.

But is it a crime?

For the second time in six years, the Minnesota Supreme Court will address that question when it rules on the constitutionality of a state law that deems it a felony for clergy members to “engage in sexual conduct” with those seeking “religious or spiritual advice, aid, or comfort in private.”

The ruling, expected soon in the case of a convicted St. Paul priest, could influence whether a Maplewood priest under scrutiny will be charged with a crime for allegedly having an affair this year with a married parishioner.

The priest in the most recent case denies the accusation, which is outlined in a search warrant issued earlier this month. The Archdiocese of St. Paul and Minneapolis, already on the defensive over allegations that it mishandled multiple cases of alleged clergy sex abuse and priest misconduct, announced last month that it has opened its own investigation. The priest, who denies the allegations, has taken a voluntary leave of absence from the Church of the Presentation of the Blessed Virgin Mary “until the matter is resolved,” the archdiocese statement said.

Maplewood police submitted their case to the Hennepin County attorney’s office, which will wait until the Supreme Court rules. “In this case, it’s not a consent issue,” said County Attorney Mike Freeman. “The question is, does it withstand constitutional muster?”

Paul Engh, an attorney who represents both priests, said it does not. Engh contends that the state law violates the Establishment Clause of the First Amendment, which holds that “Congress shall make no law respecting an establishment of religion.”

The statute includes all clergy, as well as others in positions of trust or authority, including ­psychotherapists, employees in jails or facilities, and people involved in special transportation or massage therapy or other bodywork. In each case, the statute reads, a patient’s or client’s consent to sex is not a defense.

In the case of the Maplewood priest and his accuser, Engh said no inappropriate relationships happened.

“There’s a marked difference in perception as to what had occurred,” he said.

It is typically the Star ­Tribune’s policy not to name those accused of a crime until they are formally charged.

The Wenthe appeal

The Rev. Christopher Wenthe was convicted in 2011 of third-degree criminal sexual conduct “during the course of a meeting” for a sex act that occurred with a 21-year-old woman in the rectory of Nativity of Our Lord Catholic Church in St. Paul in 2003. ­Wenthe did not dispute that the two had an 18-month relationship, but denied that it occurred while he was providing spiritual aid and comfort. He appealed his conviction, arguing that the clergy sexual conduct statute violates the Establishment Clause.

The Minnesota Court of Appeals ruled last year that the statute itself does not contradict the Establishment Clause, but that Wenthe deserved a new trial because his conviction was based on excessive religious ­evidence.

Both Wenthe and the Ramsey County attorney’s office asked the Supreme Court to hear the case, and oral arguments took place in June. The state Supreme Court does not have a deadline on which to rule, but orders are typically issued within four to five months.

It’s not the first time the Minnesota Supreme Court has weighed the question of whether the clergy sexual conduct statute is constitutional. In 2007, it decided in a 5-1 decision (Justice Lorie Gildea did not take part) to grant a new trial for ex-priest John Bussmann, who was convicted of sexually abusing two women, on the same grounds as Wenthe’s case — that the evidence against him relied too heavily on church doctrine. But they evenly split on whether the statute itself was constitutional. Because of the tie, the statute was upheld. Bussmann was convicted of a single count at his retrial.

The composition of the court has changed since the 2007 ruling. Four justices have left since then. Justices Christopher Dietzen and Wilhelmina Wright recused themselves from hearing the Wenthe case, leaving five to make the decision.

That could result in a different outcome, said Engh, who argued that a relationship between consenting adults, regardless of clergy status, should not be deemed illegal under secular law.

“The central problem with the statute is that it requires a religious definition of what spiritual aid and comfort is, and because it invites a religious definition, it interferes with the separation of church and state,” Engh said. “That is the conundrum that is facing the Supreme Court.”

Ramsey County Attorney John Choi declined to discuss the Wenthe case before the ruling is issued.

Ruling could resonate

The most recent case, involving the priest’s relationship with his married parishioner, began first with religious counseling, then dinners and board games with her family. But a search warrant affidavit chronicles a quick shift into a four-month affair that began last January and included some sexual contact.

The affidavit filed this month in Ramsey County District Court sought the priest’s personnel records from the church. According to court documents, the woman may not have been the only one he was involved with.

“And everybody you have done this with is just darn happily back at the church with you saying mass?” she asked him in a recorded telephone conversation, according to the affidavit by a Maplewood police detective.

“As far as I know, any people I’ve been involved with are still fully part of the life of the church, and whatever I’ve done with them has not caused irreparable harm to their marriages,” he allegedly responded.

Freeman said his office is looking forward to guidance when the Wenthe ruling arrives, as his office “traditionally has been very careful in charging cases.”

It’s more complicated, he said, than more clear-cut sexual abuse cases involving minors.

Engh said that, ideally, the Maplewood priest will not be charged, and Wenthe’s conviction will be overturned because the statute is found unconstitutional.

“For the very reason that religion defines what is spiritual, you can’t divorce spirit from religion under this statute,” he said. “It forces the jury to make a determination of what someone’s religion is, and that violates the separation of church and state.”