The Rev. Frank Schaefer of Lebanon could face punishment ranging from a reprimand to suspension to losing his minister's credentials if a jury composed of fellow Methodist clergy convicts him of breaking his pastoral vows by presiding over the 2007 ceremony in Massachusetts.
Jury selection began Monday morning at a Methodist retreat in Spring City, about 60 miles east of Lebanon.
Several dozen of Schaefer's supporters had lined up outside the camp's gymnasium, where the trial is taking place, wearing rainbow stoles, holding signs and singing hymns.
"I'm in support of the church becoming a new church that welcomes everyone," said Bunnie Bryant, 64, of West Chester, who was holding a sign that said: "Law or love? Jesus chose love." She continued, "I question the church's law trumping a father's love."
But a pastor who's also attending the trial says Schaefer's trial isn't about gay rights, but rather his breaking of church law and his pastoral vows.
The Rev. Judy Kehler-Shirey, a retired Methodist minister who has attended Schaefer's church, said she personally disagrees with the church's policy on gay marriage but would not officiate a same-sex wedding.
"I have a vow that is connected to all the other United Methodist pastors internationally. We have a covenant to follow the (Book of) Discipline whether we agree with it or not," she said. "That has to take priority."
The nation's largest mainline Protestant denomination accepts gay and lesbian members, but it rejects the practice of homosexuality as "incompatible with Christian teaching."
Frank Schaefer has said he informed his superiors in the Eastern Pennsylvania Conference that he planned to officiate his son's wedding, and again after the ceremony, which took place at a restaurant near Boston. He said he faced no discipline until April - about a month before the church's six-year statute of limitations was set to expire - when one of his congregants filed a complaint.
Schaefer could have avoided a trial if he had agreed to never again perform a same-gender wedding, but he declined because three of his four children are gay.
A Methodist trial resembles a secular trial in many ways, with counsel representing each side, a judge and jury, opening statements and closing arguments, and testimony and evidence. Schaefer can appeal a conviction, but neither the church nor the person who brought the charge may appeal an acquittal.