Charles Darwin's theory of evolution is widely accepted by scientists

A group of parents in the Pennsylvania town of Dover had taken the school board to court for demanding biology classes not teach evolution as fact.

The authorities wanted to introduce the theory that Earth's life was too complicated to have evolved on its own.

Judge John Jones ruled the school board had violated the constitutional ban on teaching religion in public schools.

The 11 parents who brought the case argued that teaching intelligent design (ID) was effectively teaching creationism, which is banned.

We find that the secular purposes claimed by the board amount to a pretext for the board's real purpose, which was to promote religion Judge John Jones

They complained the theory - which argues life must have been helped to develop by an unseen power - is tantamount to religious education.

The separation of church and state is enshrined in the US constitution.

In a 139-page written ruling, the federal judge said: "Our conclusion today is that it is unconstitutional to teach ID as an alternative to evolution in a public school science classroom."

Judge Jones said he had determined that ID was not science and "cannot uncouple itself from its creationist, and thus religious, antecedents".

Citizens had been "poorly served" by members of the school board who voted for the ID policy, he said.

HAVE YOUR SAY Students need to be taught both sides of the story so to speak Zahra Al-Raweshidy, UK Send us your comments

"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," he said.

"We find that the secular purposes claimed by the board amount to a pretext for the board's real purpose, which was to promote religion in the public school classroom."

The judge banned any future implementation of the policy in Dover schools.

The lawyer for the parents said the ruling was a "real vindication" for those families who had had the courage to challenge the school board.

The school board voted for "intelligent design" last year, but was itself voted out of office last month, reports BBC science correspondent Roland Pease.

It provoked US TV evangelist Pat Robertson to warn the town was invoking the wrath of God.