Government lawyers tried Tuesday to revive a 1998 law designed to keep online pornography from children, amid questions that it is significantly outdated and blocks too much legal speech while having no effect on content posted from overseas. The 3rd U.S. Circuit judges hearing the case questioned the law's effectiveness, given estimates that half of all online porn is posted overseas, beyond the reach of U.S. law. Free speech groups say the Child Online Protection Act misses the mark today, because it does not cover chat rooms, You Tube and other interactive sites that emerged in the last decade.

Lawyers with the American Civil Liberties Union, representing Salon.com and other sites that challenged the law, argue that Internet filters block 95 percent of the offensive content, and can be set to match a child's age or a parent's judgment.

But only half of all families use them, Justice Department lawyer Charles Scarborough countered.

"If there is nothing that works perfectly here, why not go with the thing that least offends the Constitution?" Judge Thomas L. Ambro asked.

Scarborough argued that the nation needs "a belt and suspenders approach" to the complex problem.

The three-judge panel did not indicate when it would rule. Last year, a federal judge who held a monthlong trial on the law deemed it an unconstitutional infringement on the First Amendment.

The Justice Department is hoping to overturn that ruling. The law has never been enforced because sexual health sites, Salon.com and other Web publishers sued and won a temporary injunction that the U.S. Supreme Court later upheld.

The law would make it a crime for Web publishers to let children access material deemed "harmful to minors" by "contemporary community standards." The sites would be expected to require a credit card number or other proof of age. Penalties include a $50,000 fine and up to six months in prison.

ACLU lawyer Chris Hansen said the government was trying to override the role of parents, who deploy various ways to monitor their children's computer use.

"I'm not here to say COPA's perfect. But filters aren't perfect either," Scarborough argued.