A federal judge rules Tuesday "intelligent design" cannot be mentioned in biology class in a Pennsylvania school district.

Judge John E. Jones III rules Dover Area School Board members violated the constitution when they ordered its biology curriculum must include the concept that life on Earth was produced by an unidentified intelligent cause.

The board's attorneys claimed members were seeking to improve science education by teaching students alternatives to Charles Darwin's theory that evolution develops through natural selection. Intelligent-design proponents argue the theory cannot fully explain the existence of complex life forms.

The plaintiffs challenging the policy argue that intelligent design amounts to a secular tweaking of creationism, which courts have already ruled cannot be taught in public schools.

The Dover policy formerly required students to hear a statement about intelligent design before ninth-grade biology lessons on evolution, stating Charles Darwin's theory is "not a fact" and has inexplicable "gaps," and referring students to an intelligent-design textbook, "Of Pandas and People," for more information.

The case is among at least a handful that have focused new attention on the teaching of evolution in the nation's schools.