What did Mahmoud Ahmadinejad learn from his controversial trip to the United States? First of all, he must be thanking his lucky stars he was not born in America. Because in America he would never have become president. There people cast their votes freely and stuffing ballot boxes and rigging elections are rare. Second, he must think Americans are terribly naïve. They gave him a platform in a leading university. And they allowed him to speak at the United Nations not far from Ground Zero, despite suspicions of Iranian involvement in the 9/11 attacks.

The visit by a man who may be one of the greatest threats to world peace today highlights America’s own struggle with freedom of speech. Should this first amendment right guarantee free speech for lies and insults, too? How can these possibly promote the common good? Ahmadinejad's speech at Columbia laid bare to the whole world America's bold, but often inconsistent, commitment to free speech. Here are five observations:

Columbia's head, Lee C. Bollinger, stressed that he had invited the Iranian president to advance the cause of free speech. "This event has nothing whatsoever to do with any 'rights' of the speaker but only with our rights to listen and speak. We do it for ourselves. We do it in the great tradition of openness that has defined this nation for many decades now." Noble sentiments. But in the mix, too, are Columbia University’s left-wing politics. Ahmadinejad was invited, not just to expose his ideas to critical scrutiny, but to flip the bird at the Bush Administration and conservatives. Bollinger taxed Ahmadinejad with human rights violations in his country, but in Columbia's eyes he did have one virtue: he also knows that George W. Bush is the Great Satan. This trivialised the noble tradition of free speech.

Newspapers reverentially report the banal opinions of famous Hollywood stars on everything from Hugo Chavez to global warming. Ahmadinejad is famous too -- even if it is for colourful remarks about the Holocaust and threatening to obliterate Israel. Why did 50 top journalists and academics accept the Iranian president's dinner invitation? To try the Intercontinental Hotel's menu? Or to hobnob with a man in the headlines? It wasn't because of his accomplishments. He hasn’t accomplished much for his fellow Iranians and 75 per cent would have been delighted if America had hung on to him. But he was famous and that alone justified his freedom of speech.

Imagine calling for the death of Iran and vowing to kill its president, then flying to Tehran for a speaking engagement at a local university. You wouldn’t last five minutes. Haleh Esfandiari is a US citizen who was jailed in Tehran in May and was only released after four months. Although she went there to visit her ailing mother, her crime is that she is director of the Middle East program at the Woodrow Wilson Center for International Scholars. A Canadian photo-journalist was captured in Tehran four years ago and tortured to death. There are no homosexuals in Iran because they are hanged.

While this drives home the point that Ahmadinejad is a murderous thug, in America even a thug is given a chance to speak. Only in America and few other countries, can a murdering dictator swagger in and blow his horn. And only in a handful of countries can journalists be allowed to freely take the dictator’s side. But it has to be so. Writes former presidential speechwriter Peggy Noonan: "If Jefferson had dined only with those who'd been a force for good in the world, Jefferson would often have dined alone. If we insist only good and moral leaders talk to us, we'll wind up surrounded by silence. In fact, if we insist we talk only to those whose good deeds have matched their high aspirations, we won't always be on speaking terms with ourselves."

While Ahmadinejad was allowed to speak at Columbia University, last year two American speakers were not. They wanted to oppose illegal Mexican immigration. Students in the audience shouted "they have no right to speak".

Last year only a small group of Columbia students and 20 guests were allowed to hear Walid Shoebat speak. He is a PLO terrorist turned anti-jihadist. He was told he was a security risk. And that is the reason why many American conservatives aren’t invited to university campuses or their talks are cancelled or interrupted. Former liberal activist David Horowitz, Islamist critic Daniel Pipes, black conservative Star Parker and numerous others frequently find themselves shouted down when they try to speak at campuses.

In Philadelphia three years ago, two demonstrations coincided. Peaceful Christians were arrested and jailed briefly. The homosexual rights demonstrators, who had been shouting and provoking them, carried on. This is the tip of a very large iceberg. A country that guarantees freedom of speech is finding that this freedom is often not tolerated when conflicting messages coincide. Increasingly, the view that is squashed is socially conservative.

Only a mature nation could provide a podium of odium in its most important city for foreign rogues and villains. In the United Nations, for many years, leaders from Nikita Kruschev and Fidel Castro to Hugo Chavez and Robert Mugabe have been driven through the streets of New York to denounce America. None would have allowed this in their own countries. For showing tremendous restraint and commitment to free speech in allowing the enemy to speak within its gates, America should be proud.