In an opinion issued Tuesday, U.S. District Judge John Jones ruled that teaching "intelligent design" would violate the Constitutional separation of church and state. "We have concluded that it is not [science], and moreover that ID cannot uncouple itself from its creationist, and thus religious, antecedents," Jones writes in his 139 page opinion posted on the court's Web site.

"To be sure, Darwin's theory of evolution is imperfect. 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," Jones writes.

Intelligent design claims the complexity of some systems of nature cannot be explained by evolution but must be attributed to a designer or supernatural being. The Dover Area School District, about 25 miles from the state capital, sought to become the first in the nation to require high school science teachers to teach the concept of intelligent design as an alternative to Darwin's theory of evolution.

Jones presided over a six-week trial that ended last month. His decision applies only to the Pennsylvania school district. His decision would block the school district's plan "requiring teachers to denigrate or disparage the scientific theory of evolution, and from requiring teachers to refer to a religious, alternative theory known as ID."

Jones says in his ruling that he did not doubt that intelligent design advocates "have bona fide and deeply held beliefs which drive their scholarly endeavors," but he also said scientific experts testified that Darwin's theory "in no way conflicts with, nor does it deny, the existence of a divine creator.