HARRISBURG, Pa. -- The latest chapter in a long-running legal debate over the teaching of evolution in public schools is about to unfold in federal court in Harrisburg.

In a civil trial set to begin Sept. 26, the Dover Area School District will defend its policy requiring ninth-grade students to hear about "intelligent design" before biology lessons on evolution.

Intelligent design holds that Charles Darwin's theory of evolution cannot fully explain the origin of life or the emergence of highly complex life forms. It implies that life on earth was the product of an unidentified intelligent force.

Critics say intelligent design is merely creationism -- a literal reading of the Bible's story of creation -- camouflaged in scientific language.

In August, the Kansas Board of Education gave preliminary approval to science standards that allow intelligent design-style alternatives to be discussed alongside evolution.

President George W. Bush has also weighed in, saying schools should present both concepts when teaching about the origins of life.