Driving home one day last December from the courthouse in Harrisburg, Pa., Judge John E. Jones III tuned in to a radio news report about 11 parents in the nearby town of Dover who had filed a lawsuit challenging their school board's decision to include intelligent design in the high school biology curriculum.

Kalim A. Bhatti for The New York Times

Judge John E. Jones III.

"It piqued my curiosity," the judge said. Not only was the suit likely to be the nation's first full hearing on the legal merits of teaching intelligent design, but it also had been filed in the federal court in Pennsylvania where he was serving.

The next morning Judge Jones turned on the computer in his chambers and found that the case had been randomly assigned to him.

"Any judge will tell you that they welcome the opportunity to have important cases on their dockets," he said in an interview. "That's why they take these jobs."

Judge Jones presided over the six-week trial with discipline, decorum and a quick wit that produced eruptions of laughter.

Next week he is expected to issue his decision, which will almost certainly be regarded as a bellwether by other school districts in which religious conservatives have proposed teaching intelligent design as a challenge to the theory of evolution.

Legal experts said the big question was whether Judge Jones would rule narrowly or more broadly on the merits of teaching intelligent design as science. Proponents of the theory argue that living organisms are so complex that the best explanation is that a higher intelligence designed them.

One of his clerks hinted last week that the decision was long.

In American courts, the battle between science and religion over the origins of life dates back 80 years to the trial of the Tennessee teacher John Scopes.

Now this political hot potato has fallen into the lap of a judge who is highly attuned to politics. He is a lifelong Republican appointed to the federal bench in 2002 by President Bush.

He ran for Congress 10 years earlier (he lost by one percentage point) and later considered running for governor. His supporters include Senators Arlen Specter and Rick Santorum of Pennsylvania, and his mentor is Tom Ridge, the former governor of Pennsylvania and homeland security secretary.

But Judge Jones is praised by people on both sides of the aisle as a man of integrity and intellect who takes seriously his charge to be above partisanship. He appears to define himself less by his party affiliation than by his connection to the Pennsylvania coal town where he still lives, and to a family that grabbed education as a rope to climb out of the anthracite mines, and never let go.

Clifford A. Rieders, a lawyer in Williamsport who is past president of the Pennsylvania Trial Lawyers Association, said he had found Judge Jones to be "moderate, thoughtful" and "universally well regarded."

"I think that his connections are not so politicized, nor is he so ambitious that he would be influenced in any way by those kinds of considerations," said Mr. Rieders, a Democrat.

Mr. Ridge called him a "renaissance man" and "the right kind of person to be presiding over a trial of such emotional and historic importance." He added, "I don't think he goes in with a point of view based on anything prior. I really don't. I think he loves the challenge."

In an interview in his chambers in Williamsport during a break in the final weeks of the trial, Judge Jones said he had been rereading Supreme Court decisions on religion.

He said he was aware that Mr. Bush and Mr. Santorum had endorsed the teaching of challenges to evolutionary theory, but he said, "It doesn't have any bearing on me."

Judge Jones said he learned speed-reading in prep school and consumes five newspapers a day before work.

He said he considered opening the Dover trial to television cameras because of "a bias in favor of disclosure." But after consulting with colleagues he decided against it. The judge said he had expected the Dover case would attract attention, but was stunned by the amount. One weekend, he said, he did a double take at a supermarket magazine rack. "I'm on the cover of the Rolling Stone!" he said to his wife. "Not my picture, but the trial." He bought a copy.

Judge Jones lives in Pottsville, a long commute from Harrisburg and Williamsport, where he hears cases. On his wall hangs a picture of his grandfather, a Welsh orphan who worked as a boy in the Pennsylvania coal mines, took correspondence courses, became a civil engineer and built a chain of golf courses.

His father, a Yale graduate, went into the family business.

The oldest of four brothers, Judge Jones, who is 50, attended a private school, Mercersburg Academy, and later Dickinson College and the Dickinson School of Law. Asked if he was religious, he said he attended a Lutheran church favored by his wife, but not every Sunday.

He had his own law firm when he ran for Congress in 1992 and lost to Tim Holden, a Democrat who had been a friend.

He helped Mr. Ridge's campaign for governor in 1994 and was later named to the board that runs the state's liquor stores. "One of these days," Mr. Ridge said in an interview, "a bunch of Republicans are going to recruit him to run for governor, but I think it's going to take a while. He loves being judge."

Of running for governor, Judge Jones said, "I wouldn't envision it, but I'm 50 years old, and it's probably imprudent to say never."

Among his cases, he has ruled that employees who refuse to authorize a background check on themselves can be fired and that a college's speech code prohibiting "acts of intolerance" violated the right to free speech.

He was reversed once on appeal in a case involving a disability claim.

In the recent trial, a lawyer grilled an intelligent design proponent on why a textbook the witness helped to write substituted "intelligent design" for "creationism" in a later edition and with "sudden emergence theory" in a draft of a future edition.

"We won't be back in a couple of years for the sudden emergence trial, will we?" the lawyer asked.

To which Judge Jones interjected, "Not on my docket."