The bishop raised his right hand yesterday, and, along with 13 fellow jurors, swore "by almighty God, the searcher of all hearts" to render a true verdict.

Thus began Bishop David Zubik's first day serving on an Allegheny County jury and fulfilling what Common Pleas Judge Kathleen A. Durkin reminded the panel of nine women and five men was "one of the most solemn duties of citizenship": to sit in judgment of a fellow citizen.

In this case, the head of the Catholic Diocese of Pittsburgh -- also known this week as Juror No. 9 -- must help decide, when testimony concludes, whether three co-defendants are guilty of breaking into a Duquesne apartment and threatening, beating, robbing and sexually assaulting various occupants.

The bustling court ran as usual all morning, with assorted guilty pleas, shackled inmates coming and going and lawyers conferring, although a sense of excitement was palpable in anticipation of the bishop's arrival.

The judge, tipstaff, minute clerk, the judge's secretary, three of four sheriff's deputies, the prosecutor and two of three defense attorneys are practicing Catholics. Two of the lawyers had rosaries in court with them.

Attorney John Knorr, who represents defendant Taneesha N. Middleton, 22, of Homestead, attended grade school at St. Elizabeth in Pleasant Hills, and was a torch boy and an altar boy through high school. He said he majored in theology at Notre Dame, clerked for Cardinal Adam Maida, the future bishop of Green Bay and archbishop of Detroit, at the diocesan legal office while he was at Duquesne Law School and later became a eucharistic minister and lector at his church.

Mr. Knorr said "it was a slam dunk to accept [the bishop] as a juror" because of his vast understanding of the human experience, but added, "I think its important to treat him as another juror." In a biblical reference to abiding by one's lay duties, he said Bishop Zubik "is rendering to Caesar today."

Prosecutor Edward Scheid was equally invigorated about choosing the bishop for the jury. Mr. Scheid, a former choir boy, said he'd attended Catholic institutions from first grade through law school at Duquesne.

Defense attorney James Sheets also attended Catholic institutions, including St. Vincent College in Latrobe and Duquesne Law School. His aunt was a nun affiliated with the Sisters of Mercy, and Mr. Sheets thought having "the bishop in the box" would cause him to tone down his sometimes flamboyant, aggressive lawyering style, but it didn't.

Assistant Public Defender Stephen Swem, a Protestant, said during jury selection that the bishop seemed as if he had all the qualities of a good juror.

As the trial progressed, courtroom observers and witnesses, who hadn't been alerted to the bishop's presence, seemed to note it all the same. One witness, who was subjected to rigorous cross-examination by Mr. Sheets, said seeing the man with the white collar, clerics and crucifix in the jury box kept him from losing his cool on the stand.

A friend of one of the co-defendants asked another person in the gallery, "Is that dude a priest?"

The jurors were released a bit early for lunch because one of the jurors had a prior commitment, the judge said.

It turned out Bishop Zubik was scheduled to speak to a group of about 40 judges, lawyers and canonical lawyers at Buchanan Ingersoll & Rooney. He gave the yearly George Loebig lecture to the St. Thomas More Society, an organization of Catholic lawyers in the Pittsburgh Diocese. A St. Thomas More board member noted that the current bishop always gives the lecture, but it was "highly unusual" he was on jury duty at the same time.

In a 45-minute address about "moral relativism" and a pastoral letter he'd just written, he mentioned that one of his fellow jurors had been reading the Catechism of the Catholic Church in the waiting area and "lo and behold, look who sits next to him." Another juror asked him during a break what he thought about introducing lesser priests into the church, he said.

He joked that he had to get back, unless one of the lawyers present wanted to represent him before his judge.

The bishop returned to court for more hours of testimony.

His spokesman, Rev. Ronald P. Lengwin, said although he has a packed schedule, the bishop is "very pleased he was not dismissed" from duty. He "thinks that it's a privilege to serve on the jury" and "contribute to the well being of the community."

Both in Allegheny County and in Green Bay, Wis., his spokesman said, "he's been called to serve but was never selected before."