They dressed as Uncle Sam and arrived decked out in the Stars and Stripes in cinemas all across the United States on Christmas Day for the premiere of the anti-North Korean spoof movie The Interview. One cinema manager introduced the Sony film by reciting "My Country 'Tis of Thee". A coarse comedy – in which a pair of bumbling journalists are recruited by the CIA to assassinate North Korean premiere Kim Jong-un – became an improbable symbol of free speech.

"I'm here to show support for the US," said one university professor. And, added another ticket-buyer, "to show that we don't take any garbage from those guys in North Korea". One cinema manager concluded: "We are taking a stand for American values," and then added, without evident irony, "and hoping to make some money from the movie."

It all seemed a reductio ad absurdum of the high-minded arguments of freedom of expression advanced by Democrats in Hollywood and Republicans in Washington.

Sony Cyber Attack: The Worst Affected In Hollywood Show all 13 1 /13 Sony Cyber Attack: The Worst Affected In Hollywood Sony Cyber Attack: The Worst Affected In Hollywood Leonardo DiCaprio The actor's 'horrible behaviour' over Steve Jobs biopic was branded 'actually despicable' in leaked Sony executive emails Getty Images Sony Cyber Attack: The Worst Affected In Hollywood Seth Rogen Seth Rogen and James Franco cancel Interview (North Korea-baiting film) press appearances after Sony hackers' threats Sony Cyber Attack: The Worst Affected In Hollywood James Franco Seth Rogen and James Franco cancel Interview press appearances after Sony hackers' threats AP Sony Cyber Attack: The Worst Affected In Hollywood Aaron Sorkin The screenwriter has said that the people who hacked into Sony Entertainment Pictures and released private emails are 'threatening the lives of whole families' Theo Wargo | Getty Images for Nantucket Film Festival Sony Cyber Attack: The Worst Affected In Hollywood Amy Pascal Also leaked: Sony Pictures co-chair Amy Pascal's email joking about President Barack Obama's race Getty Images Sony Cyber Attack: The Worst Affected In Hollywood George Clooney Leaked email chain between Pascal and George Clooney appeared to reveal just how much the actor struggled to cope with the criticism of his The Monuments Men Getty Sony Cyber Attack: The Worst Affected In Hollywood Barack Obama Sony executives Scott Rudin and Amy Pascal's leaked email exchange jokes about Barack Obama favouring films with black actors Getty Sony Cyber Attack: The Worst Affected In Hollywood Channing Tatum Channing Tatum's leaked Sony executive email responding to the success of 22 Jump Street with Jonah Hill, which became the highest grossing R-rated comedy ever when it opened in June this year Getty Images Sony Cyber Attack: The Worst Affected In Hollywood Jaden and Willow Smith Will Smith and Jada Pinkett Smith's children Willow and Jaden Smith found themselves in the Sony inbox as well Getty Sony Cyber Attack: The Worst Affected In Hollywood Mark Gordon DiCaprio's exchange with Jobs TV producer Mark Gordon (pictured) was leaked too Getty Images Sony Cyber Attack: The Worst Affected In Hollywood Princess Beatrice Sony hackers linked to North Korea revealed Princess Beatrice earns $30,000 a year Sony Cyber Attack: The Worst Affected In Hollywood Michael Fassbender Aaron Sorkin's leaked emails claimed he had no idea who actor Michael Fassbender (pictured) was Getty Images Sony Cyber Attack: The Worst Affected In Hollywood Scott Rudin Information leaked has also included embarrassing emails involving high profile producer Scott Rudin attacking Angelina Jolie Getty Images

In at least one cinema, however, the audience fell silent when the scene arrived in which Kim Jong-un dies as his helicopter is downed and Mr Kim's head explodes. Perhaps for a moment they took on board why the North Koreans have reacted so aggressively, complaining to the United Nations that "such a film on the assassination of an incumbent head of a sovereign state" was tantamount to an "undisguised sponsoring of terrorism".

Defending freedom of speech, Voltaire is frequently summarised as having said: "I disapprove of what you say, but I will defend to the death your right to say it." In other words, we know whether we really defend free speech only when someone says something with which we seriously disagree.

Watch more

Freedom of speech is not, of course, absolute. Few would defend the right of a liar to shout "fire" in a crowded cinema, though the ethics might possibly be more problematic if the shouter were a North Korean protester. But even though freedom of expression is essential to the full flow of information needed for a participative democracy to work, we nonetheless place constraints on it.

Free speech is not the right to say whatever you like, about whatever or whomever you like, whenever you like. As a society we routinely restrict freedom of speech to keep the nation safe, maintain public order, ensure individuals have fair trials, preserve copyright or trade secrets, prevent the incitement of racial or religious violence, outlaw degrading pornography and protect children.

And even where speech is unfettered, having the right to say something does not mean it is always wise to do so. Danish newspapers had the right to publish anti-Islamic cartoons of the Prophet Mohamed wearing a bomb in his turban. But the violent reactions from Muslims around the world, in which several people died, suggested that the editor of the paper that did publish might have been better to have exercised the virtue of self-restraint.

It is not to deny the right of free expression to suggest that publishers have responsibilities as well as rights. Google acknowledged that more recently when it pulled an incendiary anti-Islamic video in Egypt and Libya, after the killing of a US ambassador and three other Americans. It might have been useful had it considered the issue before the deaths.

The unfettered exercise of a right can bring unpredicted consequences – as Sony executives learned when the movie corporation's confidential data was released on to the internet and its hard drives wiped.

Yet such is the binary nature of modern American politics that it proved impossible for even a President as subtle and intelligent as Barack Obama to acknowledge even a flicker of this complexity. He could have made points about the distinction between the acts of a US citizen or corporation and those of its government. Instead he blundered in with an undifferentiated declaration, as if free speech were a right which trumped all others. Sony had made a mistake, he declared, and paved the way for censorship by foreign dictators.

The North Korean government in Pyongyang has denied it was behind the attack – which it has nonetheless praised as a "righteous deed". Mr Obama, on the advice of the FBI, does not believe that and responded by saying: "They caused a lot of damage, and we will respond. We will respond proportionally, and we'll respond in a place and time and manner that we choose.

Such a knee-jerk response has not gone down well among other major powers. The Russian foreign minister has described the film as described as "aggressively scandalous" and lamented Mr Obama's "threats to take revenge". And the Chinese, despite their increasing irritation with Kim Jong-un's preposterous and cruel behaviour, have refused to agree to Washington's requests to block North Korean cyber-traffic, which mainly passes through China. One government mouthpiece in Beijing has spoken of America's "senseless cultural arrogance".

It's not hard to see what they mean when you consider Hollywood's highly selective targeting of Russia, Iran, North Korea and Islamists in its limited search for cinematic villains. Hollywood needs to show greater imagination or, as Beijing suggested, better manners.

Good manners may well bear more fruit in international diplomacy than does talk of rights or even responsibilities. Sad, then, that the response of a body in the US which calls itself the Human Rights Foundation is to suggest it will buy copies of the dubious film and drop them from balloons flying over North Korea.

The problem here is not freedom of speech but adolescent arrogance. The United States would do well to ignore North Korea's childish monkey jibe and finally to put an end to its Wild West tendency to shoot its mouth off first and ask questions later.