Yesterday a 3rd U.S. Circuit Court of Appeals in Philadelphia struck down as unconstitutional the “Child Online Protection Act:, a 1998 law intended to protect children from sexual material and other objectionable content on the Internet.

This law has been fought in the courts for over a decade. The fight has already reached the Supreme Court and could be headed back there.

The law, which has never taken effect, would bar Web sites from making “harmful content” available to minors over the Internet.  It would greatly restrict what adult site could show in banner ads, on its “free tour” pages and in in advertising and marketing on the net.

The act was passed the year after the Supreme Court ruled that another law intended to protect children from explicit material online unconstitutional, the “Communications Decency Act” which was challenged by the ACLU and a coalition of writers, artists, health educators and the publisher Salon Media Group.

ACLU attorney Chris Hansen argued that Congress has been trying to restrict speech on the Internet far more than it can restrict speech in books and magazines. But, he said, “the rules should be the same.”

The Child Online Protection Act would effectively force all Web sites to provide only family friendly content because it is not feasible to lock children out of sites that are lawful for adults, said John Morris, general counsel for the Center for Democracy & Technology, a civil liberties group that filed briefs against the law.

In its ruling Tuesday, the federal appeals court concluded that the Child Online Protection Act is unconstitutionally overly broad and vague.

The court also ruled that the law violates the First Amendment because filtering technologies and other parental control tools offer a less restrictive way to protect children from inappropriate content online.

The courts have constientially held that filters provide a more effective way to protect children since they can also block objectionable Web sites that are based overseas, beyond the reach of U.S. law.