A federal judge in Pennsylvania has dealt a legal setback to supporters of an alternative theory of evolution known as intelligent design. 

Federal Judge John Jones ruled the religiously inspired theory of intelligent design cannot be taught alongside Charles Darwin's theory of evolution in classrooms in a Pennsylvania school district.

Intelligent design hinges on the belief that a higher power created life and that Darwin's theory of evolution does not fully explain the origins of mankind.

School board members in Dover, Pennsylvania, decided last year that students should be made aware of intelligent design when they study evolution.

But in his ruling Tuesday, Judge Jones said Dover Area school board members violated the constitutional prohibition against mixing church and state when they made that order.

Judge Jones also said board members who supported intelligent design repeatedly lied about their real purpose, which he said was to promote a religious view of evolution known as creationism.

Opponents of intelligent design hailed the judge's ruling as a major legal victory that would have national implications.

Barry Lynn heads an organization called Americans United For Separation of Church and State.

"This is an organized campaign by the so called religious right to turn public schools into Sunday schools and to teach their religious doctrines there," said Mr. Lynn.  "The decision today is a big roadblock to that crusade of the right."

Supporters of intelligent design argue there is nothing wrong with making public school students aware of an alternative view of evolution.

Casey Luskin is an activist on behalf of intelligent design.

"This is a scientific theory," said Mr. Luskin.  "We believe the judge got it wrong in equating intelligent design with creationism.  So, this is a loss for education as a whole and, in that sense, we are absolutely disappointed."

The Supreme Court banned the teaching of the religion-based theory of creationism in public schools in 1987, ruling that it violated the constitutional mandate of keeping church and state separate.

Eight members of the Dover area school board who support intelligent design were defeated in local elections last month.