When Congress passed the PROTECT Act in 2003, lawmakers made it clear that "efforts to stimulate, feed or capitalize on a market for what purports to be child pornography deserve no sanctuary," the U.S. Solicitor General's office insists.

The declaration came in court papers filed in the case of Michael Williams, arrested in Florida and subsequently convicted in an undercover operation aimed at combating child exploitation on the Internet.

A Secret Service agent engaged Williams in an Internet chat room, where they swapped non-pornographic photographs. After the initial photo exchange, Williams is alleged to have posted seven images of actual minors engaging in sexually explicit conduct. Agents who executed a search warrant found 22 child porn images in Williams' home.

But the conviction was subsequently reversed by the 11th U.S. Circuit Court of Appeals, which found the pandering provision of the PROTECT Act overbroad and impermissibly vague.

Just as narcotics officers grew frustrated trying to prosecute "drug dealers" who peddle oregano in place of marijuana -- and subsequently persuaded state legislatures to ban even such a pretence of drug dealing -- so does this federal law impermissibly criminalize the speech of someone who touts material as child pornography when in fact it is clean or nonexistent, the appeals court held.

Furthermore, the law creates what amounts to a thought crime -- punishing an otherwise innocent act based on an attempt to read the perpetrator's intent.

For example, the pandering provision could be applied to an e-mail sent by a grandparent with a subject line of "Good pics of kids in bed," and innocent photos of grandchildren in pajamas attached, the court held.

One sender might be a proud grandparent, while another might be a child molester hoping to trade for more graphic photos with like-minded recipients. A law that could sweep up the former along with the latter is certainly "impermissibly vague."

Obviously, having sex with young children or purposely posing them in sexually explicit situations is illegal and should be. The question here is not the wisdom of attempting to stop this exploitation of children, but to what extent such efforts impermissibly chill and infringe on the rights of non-child-molesting adults to speak freely and to live free of unwarranted government snooping and entrapment.

On Monday, the U.S. Supreme Court agreed to take up the Williams case on appeal, bravely volunteering to unsnarl this particular thorn bush.

The goals of the Congress here are understandable. But in a nation where constitutional freedoms are paramount, the court must often err on the side of free rein for those freedoms, even if it presents the authorities with a heavier burden.