A Presbyterian minister accused of marrying two lesbian couples in violation of the faith's position that marriage is between a man and a woman could face a reprimand or be forced to leave the ministry after more than 30 years.

The Rev. Jane Spahr of San Rafael was scheduled to be tried by a church judicial commission on Thursday for the ceremonies, conducted in 2004 and 2005.

Spahr, 63, argues she was honoring her personal conscience and relationship with God when she officiated at the ceremonies. If found guilty by the regional governing body of the Presbyterian Church (USA), the Presbytery of the Redwoods, she could face anything from a rebuke to being removed from the ministry, said one of her lawyers, Timothy Cahn.

"Faith communities have enormous responsibility to fight oppressive systems," said Spahr, a lesbian activist who directs a group lobbying for greater inclusion of gay Presbyterians in the church. "Certainly the founder of the Christian faith was someone who challenged all oppressive systems that kept people from being whole."

The Presbyterian Church (USA) is among several Protestant denominations embroiled in a bitter debate between liberals and conservatives over what role gays should have in their churches. Under a ruling by the national church's highest court in 2000, Presbyterian churches may bless same-sex unions as long as they do not equate the relationships with marriage.

Spahr is one of a half-dozen Presbyterian ministers across the nation facing disciplinary action for marrying same-sex couples, although her case is the first to come to trial, Cahn said. The others include the Rev. Jim Rigby in Austin, Texas, the Rev. Janet Edwards in Pittsburgh and the Rev. Ilene Dunn in San Antonio.

Cahn said the defense seeks to clarify whether the 2000 church court ruling is at odds with the church's historical position giving ministers broad discretion in how they interpret the faith to meet the needs of their congregations.

"The court says ministers must differentiate — same-sex holy unions and marriage for everyone else," Cahn said. "Janie's conduct is challenging that."

As the regional arm of the church, the presbytery is responsible for investigating misconduct charges leveled against its member clergy. At issue is if Spahr violated the part of the church constitution defining marriage as "a covenant through which a man and a woman are called to live out together before God their lives in discipleship."

Robert Conover, stated clerk of the Presbytery of the Redwoods, said a complaint against Spahr was brought by another minister from outside the area.

"We didn't go looking for this," Conover said.

The church does not allow actively gay or lesbian members to serve as ministers, although Spahr, who was ordained in 1974, was allowed to keep her position after she came out as a lesbian in 1978.

She has been prohibited from leading an individual church since 1991, however, and since then has worked for two churches as a "lesbian evangelist" and director of That All May Freely Serve, a group lobbying for ordination of gay and lesbian Presbyterians.

Besides Spahr, witnesses at the trial are expected to include the two couples she married, Connie Valois and Barbara Jean Douglass, of Rochester, N.Y., and Annie Senechal and Sherrill Figuera, of Guerneville.