On Tuesday, the Supreme Court will again enter the debate over curbing Internet porn. Congress has repeatedly attempted to criminalize the use of the Internet for seling or acquiring child pornography only to have opinions striking down its language on first amendment grounds.

At issue in United States v. Williams is a 2003 law that criminalizes the advertising of purported child pornography that has been challenged by an assortment of publishers and first amendment groups as too broad.

These challenges mirror prior cases where free speech won over congressional power. In 2002, the court struck down a 1996 law against “virtual” child porn as covering legitimate publications with sexual content or imagery. Congress rewrote the law but again used sweeping language that criminalizes efforts to advertise, promote, distribute or solicit materials purported to show children in sexually explicit acts — even when such material does not actually exist.

The defendant in the case is Michael Williams, who included this message in a chat room: “Dad of toddler has ‘good’ pics of her and me for swap of your toddler pics, or live cam.” In a string operation, agents obtained a search warrant of his home and found child pornography. He was given two five-year terms under the law.

The U.S. Court of Appeals for the 11th Circuit struck down the law after too broad under the First Amendment. In my view, the court was right. The language in the statute is breathtakingly vague. The problem with this crime is that it is hard to encompass the full range of criminal activity without sweeping non-criminal conduct into the scope of the definition. Congress, however, is addicted to such bills. There is nothing more popular than fighting child porn despite the fact that few people are expected to be prosecuted on this particular provision. Congress has often sacrificed free speech for political popularity. In teh past, the Supreme Court has stood in the way, making the unpopular but right decision.

This case is likely to be a close call with a new court, particularly with the addition of Sam Alito, who is known to be exceptionally pro-government in criminal cases and has never shown much concern over first amendment issues in such cases. It could come down to Kennedy, once again — leaving this a Court of one. This is precisely why I have advocated the expansion of the Supreme Court to avoid such great social and legal issues being decided by a handful of individuals — or a single individual. For the earlier column, click here