Conservative Leader Stephen Harper's election campaign hit a low point with his decision to play politics with the inflammatory issue of child pornography. His actions cast doubt not just on his commitment to free expression, but his powers of judgment.

The issue broke out on Friday when the Conservatives issued a press release bearing the headline "Paul Martin Supports Child Pornography?" It suggested that by voting against an Alliance party motion on child porn, the Liberal government had shown its lack of commitment to cleaning up the scourge -- an outrageous comment to make just a day after the sentencing of the killer of Toronto's Holly Jones, who said his desires were fuelled by porn.

The Conservatives quickly withdrew the release, but, when confronted with it, Mr. Harper refused to apologize. Instead, he stepped up the attack. "The substance of the attack is clearly true and that is that Mr. Martin and the Liberal Party have in fact been soft on porn," he said. The next day, he went further, saying that Mr. Martin had "misrepresented -- I'm tempted to say he lied -- about his position." Mr. Harper claimed: "The position of the Liberal Party allows substantial exceptions for child pornography and it was not his No. 1 priority. . . . He didn't pass legislation on the matter."

What nonsense. Canada has a tough child-porn law, brought in by the Liberals, that among other things provides for sentences of up to 10 years in jail for putting child porn on the Internet. An even tougher bill was in the works but did not make it through Parliament before the election, a common fate for legislation.

The "exception" Mr. Harper refers to is the "public good" defence, which would exempt writers, artists, researchers and legal authorities from prosecution in some circumstances. Without it, the police could potentially break down your door for owning a copy of Vladimir Nabokov's Lolita. Is that the kind of Canada that Mr. Harper wants? To include such a sensible and necessary clause in the bill does not make the Liberals "soft" on porn.

Mr. Harper is an intelligent man and he must know this. His judgment should have told him that to throw such a slur at Mr. Martin was the grubbiest kind of politics. He owes Mr. Martin, and the country, an apology.