As a government entity, a school cannot allow some clubs and prohibit others on the basis of the content of their speech. For example, a school could not allow a club of young Republicans but prohibit a club of young Socialists. A school could not allow a club of students who wanted to discuss a creationist approach to evolution but deny a club that wanted to discuss a Darwinian approach to evolution. Government entities, including schools, cannot pick and choose on the basis of the content of the club or group wishing to associate. There are limits, however; they don't have to allow a club that builds terrorists bombs or which plot over-throwing the government. The don't have to allow groups engaged in hateful speech or activities, such as the Klu Klux Klan--though even that prohibition might be debatable. Schools that infringe free speech and association are violating civil rights, which is actionable in a U.S. district court.
