A federal judge yesterday ruled unconstitutional a Pennsylvania school district’s policy to inform students in biology classes about “intelligent design,” an alternative to the theory of evolution.

In a 139-page opinion, Judge John Jones found that intelligent design, which holds that life is so complex it must have been crafted by a thoughtful, external force, cannot be divorced from the story of creation advanced by major world religions.

In unusually harsh language for a court ruling, the judge railed against the Dover, Pa., school board’s decision to adopt the policy as an act of “breathtaking inanity” that was obviously religiously motivated. He also found that during a six-week trial earlier this year, the school board failed to show that intelligent design can be considered science.

“Not one defense expert was able to explain how the supernatural action suggested by ID could be anything other than an inherently religious proposition,” Judge Jones wrote. “The over whelming evidence at trial established that ID is a religious view, a mere relabeling of creationism, and not a scientific theory.”

Judge Jones also pilloried school board members who supported the teaching of intelligent design, accusing them of telling “outright lies” to cover up the religious aspects of their effort.

“The citizens of the Dover area were poorly served by the members of the board who voted for the ID policy,” the judge 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 ID policy.”

A Seattle-based think tank which promotes the teaching of intelligent design, the Discovery Institute, said Judge Jones overstepped his bounds. “The Dover decision is an attempt by an activist federal judge to stop the spread of a scientific idea and even to prevent criticism of Darwinian evolution through government-imposed censorship and it won’t work,” an official with the institute, John West, said in a written statement. “Judge Jones got on his soapbox to offer his own views of science, religion and evolution. He makes it clear that he wants his place in history …This is an activist judge who has delusions of grandeur.”

In his opinion, Judge Jones predicted, accurately, that his decision would be denounced by some as judicial activism. However, the judge, a Republican appointed by President Bush, said the true troublemakers were the school board members and attorneys from a Michigan-based legal group devoted to defending the religious freedom of Christians, the Thomas More Law Center.

“This case came to us as the result of the activism of an ill-informed faction on a school board, aided by a national public interest law firm eager to find a constitutional test case on ID, who in combination drove the board to adopt an imprudent and ultimately unconstitutional policy,” the judge wrote. “The students, parents, and teachers of the Dover Area School District deserved better than to be dragged into this legal maelstrom, with its resulting utter waste of monetary and personal resources.”

The lawsuit that led to yesterday’s decision was brought on behalf of local residents by the American Civil Liberties Union of Pennsylvania and Americans United for the Separation of Church and State. It was not clear yesterday whether the judge’s ruling would be appealed. Several members of the school board who voted for the policy were defeated in an election last month by candidates who oppose the teaching of intelligent design. Without an appeal, the case will have no formal effect in other disputes, though other judges may choose to follow Judge Jones’s reasoning.

A former board member who pushed for the intelligent-design policy, William Buckingham, said the judge’s ruling was misguided. “It seems pretty much to center on the separation of church and state. That doesn’t exist in the Constitution,” said Mr. Buckingham, who cited health problems when he resigned from the board this summer and moved to South Carolina.

Mr. Buckingham, who was among those Judge Jones accused of lying to stymie the lawsuit, reacted angrily to the charge. “If he says I’m a liar, he’s lying,” the former board member and police officer said. “I answered the questions at the time the way they asked them. If they don’t know how to ask a question, it’s not my fault.”

While the dispute is often cast as one about the teaching of intelligent design, the policy adopted by the Pennsylvania school district last year did not call for adding the alternative theory to the curriculum. The district required that students be read a brief statement that the theory of evolution “is not a fact” and that “gaps in the theory exist for which there is no evidence.” The statement also referred students to a book, “Of Pandas and People,” for further information on intelligent design.

In an interview in August, Mr. Bush appeared to side with those who favor teaching intelligent design, though he said the matter should be left to local officials. “Both sides ought to be properly taught,” Mr. Bush said. “Part of education is to expose people to different schools of thought.”