HARRISBURG, Pa. — Attorneys clashed in a federal courtroom yesterday as a trial over the teaching of intelligent design and evolution came to an end.

In final arguments, both sides said they had waged the six-week legal battle to defend children's rights to learn and think critically about science in public schools.

The case grew out of a decision last year by school board members in Dover, Pa., to tell biology students about intelligent design — a theory that living organisms are so biologically complex that they were created by a "designer." Many backers of the concept say they believe that designer is God. Eleven parents sued the school district, hoping to overturn the decision. They argued that intelligent design has distinctly religious overtones, and is a thinly-disguised attack on Charles Darwin's widely accepted theory of evolution.

"Intelligent design does not belong in a high school biology class. ... It is an inherently religious doctrine that is a modern form of creationism, and this shell game has to end," said Eric Rothschild, representing the plaintiffs. "This board wanted to trash evolution, not to teach it. It wanted to impose its religious views on others."

Patrick Gillen, representing the school board, called intelligent design "the next big paradigm shift in scientific thinking," and said the Dover School board wanted "to teach children how to think, not what to think. This was all about learning."

A ruling by U.S. Judge John E. Jones in the non-jury trial is expected next month.

At issue is a four-paragraph statement that the board said should be read to biology students. The statement says there are "gaps" in Charles Darwin's theory of evolution, and that intelligent design offers a different explanation. Students are also told that copies of a book about intelligent design are available in the library.

The plaintiffs, who were represented by the American Civil Liberties Union and Americans United for Separation of Church and State, argued that Dover school board officials acted for religious reasons. They also contended that intelligent design is no different from creationism, a Bible-based view of the origins of life that the U.S. Supreme Court banned from public schools in a 1987 ruling.

Defendants were represented by the Thomas More Law Center, a legal group that promotes and defends the religious freedoms of Christians. They argued that school board members, who were the first in the United States to make intelligent design part of the curriculum, had expressed valid personal doubts about evolution.

William Buckingham, a former member who backed the intelligent design plan, said in one meeting that the theory should be taught because "nearly 2,000 years ago someone died on a cross for us. Shouldn't we have the courage to stand up for him?"

During the trial, Buckingham denied having made those comments, which were reported in two local newspapers. But plaintiffs then played the tape of a local TV news broadcast in which Buckingham said he did not want to approve a standard biology textbook for Dover students because "the book is laced with Darwinism. It's OK to teach Darwin, but you have to balance it with something else, like creationism."

Attorneys also disagreed over the merits of intelligent design. Gillen said the academics who embrace it "are in the minority, like all discoverers." He added that "intelligent design is science, it is not religion. Evolution is just a theory, not a fact."

Rothschild, however, noted that most scientists reject intelligent design, because it is a subjective idea that has not been tested or proved in a scientific setting.