In the nation's first case to test the legal merits of intelligent design, the judge, John E. Jones III, issued a broad, stinging rebuke to its advocates and provided strong support for scientists who have fought to bar intelligent design from the science curriculum.
Judge Jones also excoriated members of the Dover, Pa., school board, who he said lied to cover up their religious motives, made a decision of "breathtaking inanity" and "dragged" their community into "this legal maelstrom with its resulting utter waste of monetary and personal resources."
Eleven parents in Dover, a growing suburb about 20 miles south of Harrisburg, sued their school board a year ago after it voted to have teachers read students a brief statement introducing intelligent design in ninth-grade biology class.
The statement said that there were "gaps in the theory" of evolution and that intelligent design was another explanation they should examine.
Judge Jones, a Republican appointed by President Bush, concluded that intelligent design was not science, and that in order to claim that it is, its proponents admit they must change the very definition of science to include supernatural explanations.
Judge Jones said that teaching intelligent design as science in public school violated the First Amendment of the Constitution, which prohibits public officials from using their positions to impose or establish a particular religion.
"To be sure, Darwin's theory of evolution is imperfect," Judge Jones wrote. "However, the fact that a scientific theory cannot yet render an explanation on every point should not be used as a pretext to thrust an untestable alternative hypothesis grounded in religion into the science classroom or to misrepresent well-established scientific propositions."
The six-week trial in Federal District Court in Harrisburg gave intelligent design the most thorough academic and legal airing since the movement's inception about 15 years ago, and was often likened to the momentous Scopes case that put evolution on trial 80 years earlier.
Intelligent design posits that biological life is so complex that it must have been designed by an intelligent source. Its adherents say that they refrain from identifying the designer, and that it could even be aliens or a time traveler.
But Judge Jones said the evidence in the trial proved that intelligent design was "creationism relabeled."
The Supreme Court has already ruled that creationism, which relies on the biblical account of the creation of life, cannot be taught as science in a public school.
Judge Jones's decision is legally binding only for school districts in the middle district of Pennsylvania. It is unlikely to be appealed because the school board members who supported intelligent design were unseated in elections in November and replaced with a slate that opposes the intelligent design policy and said it would abide by the judge's decision.
Lawyers for the plaintiffs said at a news conference in Harrisburg that the judge's decision should serve as a deterrent to other school boards and teachers considering teaching intelligent design.
"It's a carefully reasoned, highly detailed opinion," said Richard Katskee, assistant legal director of Americans United for Separation of Church and State, "that goes through all of the issues that would be raised in any other school district."
Richard Thompson, the lead defense lawyer for the school board, derided the judge for issuing a sweeping judgment in a case that Mr. Thompson said merely involved a "one-minute statement" being read to students. He acknowledged that his side, too, had asked the judge to rule on the scientific merits of intelligent design, but only because it had to respond to the plaintiffs' arguments.
"A thousand opinions by a court that a particular scientific theory is invalid will not make that scientific theory invalid," said Mr. Thompson, the president and chief counsel of the Thomas More Law Center, a public interest firm in Ann Arbor, Mich., that says it promotes Christian values. "It is going to be up to the scientists who are going to continue to do research in their labs that will ultimately determine that."
The scientists who have put intelligent design forward as a valid avenue of scientific research said they were disappointed by Judge Jones's ruling but that they thought its long-term effects would be limited.
"That was a real drag," said Michael J. Behe, a professor of biochemistry at Lehigh University who was the star witness for the intelligent design side. "I think he really went way over what he as a judge is entitled to say."
Dr. Behe added: "He talks about the ground rules of science. What has a judge to do with the ground rules of science? I think he just chose sides and echoed the arguments and just made assertions about our arguments."
William A. Dembski, a mathematician who argues that mathematics can show the presence of design in the development of life, predicted that intelligent design would become much stronger within 5 to 10 years.
Both Dr. Behe and Dr. Dembski are fellows with the Discovery Institute, a leading proponent of intelligent design.
"I think the big lesson is, let's go to work and really develop this theory and not try to win this in the court of public opinion," Dr. Dembski said. "The burden is on us to produce."
Mainstream scientists who have maintained that no controversy exists in the scientific community over evolution were elated by Judge Jones's ruling.
"Jubilation," said Kenneth R. Miller, a professor of biology at Brown University who has actively sparred with intelligent design proponents and testified in the Dover case. "I think the judge nailed it."
Dr. Miller said he was glad that the judge did not just rule narrowly.
Jason D. Rosenhouse, a professor of mathematics at James Madison University in Virginia and a fervent pro-evolution blogger said: "I was laughing as I read it because I don't think a scientist could explain it any better. His logic is flawless, and he hit all of the points that scientists have been making for years."
Before the start of a celebratory news conference in Harrisburg, Tammy Kitzmiller, a parent of two daughters in the Dover district and the named plaintiff in the case, Kitzmiller et al v. Dover, joked with other plaintiffs that she had an idea for a new bumper sticker: "Judge Jones for President."
Christy Rehm, another plaintiff, said to the others, "We've done something amazing here, not only with this decision, but with the election."
Last month, Dover, which usually votes majority Republican, ousted eight school board members who had backed intelligent design and elected the opposition that ran on a Democratic ticket.
Witold Walczak, legal director of the American Civil Liberties Union of Pennsylvania, who helped to argue the case, said, "We sincerely hope that other school districts who may have been thinking about intelligent design will pause, they will read Judge Jones's erudite opinion and they will look at what happened in the Dover community in this battle, pitting neighbor against neighbor."
The judge's ruling said that two of the most outspoken proponents of intelligent design on the Dover school board, William Buckingham and Alan Bonsell, lied in their depositions about how they raised money in a church to buy copies of an intelligent design textbook, "Of Pandas and People," to put in the school library.
Both men, according to testimony, had repeatedly said at school board meetings that they objected to evolution for religious reasons and wanted to see creationism taught on equal footing.
Judge Jones wrote, "It is ironic that several of these individuals, who so staunchly and proudly touted their religious convictions in public, would time and again lie to cover their tracks and disguise the real purpose behind the I.D. policy."
Mr. Bonsell did not respond to a telephone message on Tuesday. Mr. Buckingham, a retired police officer who has moved to Mount Airy, N.C., said, "If the judge called me a liar, then he's a liar."
Mr. Buckingham said he "answered the questions the way they asked them." He called the decision "ludicrous" and said, "I think Judge Jones ought to be ashamed of himself."
The Constitution, he said, does not call for the separation of church and state.
In his opinion, Judge Jones traced the history of the intelligent design movement to what he said were its roots in Christian fundamentalism. He seemed especially convinced by the testimony of Barbara Forrest, a historian of science, that the authors of the "Pandas" textbook had removed the word "creationism" from an earlier draft and substituted it with "intelligent design" after the Supreme Court's ruling in 1987.
"We conclude that the religious nature of intelligent design would be readily apparent to an objective observer, adult or child," the judge said. "The writings of leading I.D. proponents reveal that the designer postulated by their argument is the God of Christianity."
Opponents of intelligent design said Judge Jones's ruling would not put an end to the movement, and predicted that intelligent design would take on various guises.
The Kansas Board of Education voted in November to adopt standards that call into question the theory of evolution, but never explicitly mention intelligent design.
Eugenie Scott, executive director, National Center for Science Education, an advocacy group in Oakland, Calif., that promotes teaching evolution, said in an interview, "I predict that another school board down the line will try to bring intelligent design into the curriculum like the Dover group did, and they'll be a lot smarter about concealing their religious intent."
Even after courts ruled against teaching creationism and creation science, Ms. Scott said, "for several years afterward, school districts were still contemplating teaching creation science."