How do you insult someone legally?
Campaigners want to overturn laws targeting "insulting words and behaviour". Just how safe is it to scorn others?
British public life has a lengthy and noble tradition of well-crafted insults.
Shakespeare's "thou hast no more brain than I have in mine elbows". Winston Churchill's comparison of Charles de Gaulle to a "female llama who has been surprised in the bath". Dennis Healey likening a parliamentary attack by Sir Geoffrey Howe to being "savaged by a dead sheep".
But not all barbs are quite so erudite. For every Churchillian bon mot, many more are made to abuse, intimidate and frighten.
For decades the law has sought to regulate the latter categories. In 1986, section five of the Public Order Act made it illegal to engage in "insulting words or behaviour" in England and Wales.
But a backlash has been brewing amid concerns that efforts to protect the public's sensibilities have gone too far.
A campaign called Feel Free To Insult Me has been launched to lobby for section five's repeal, citing a series of cases when the legislation attracted criticism and ridicule.
In one well-publicised 2006 incident, an Oxford University student was arrested after asking a mounted police officer if he realised his horse was "gay". Two years later a teenager was charged after demonstrating outside the London headquarters of the Church of Scientology with a placard declaring that Scientology was not a religion but "a dangerous cult".
Another case saw a pair of Christian hoteliers put on trial after they were wrongly accused of asking a Muslim guest if she was a murderer and a terrorist because she was wearing a hijab.
None of these incidents resulted in a successful prosecution - charges against the Oxford student and the Scientology protester were eventually dropped, while a judge dismissed the case against the hoteliers.
Nonetheless, opponents fear that the public has become inhibited from speaking openly.
The campaign against section five has forged some unlikely alliances, with left-wing human rights activist Peter Tatchell backing it alongside Conservative MP David Davis and Nigel Farage, leader of the UK Independence Party. Also lending their support are both the Christian Institute and the National Secular Society.
According to Tatchell - who was himself charged in 1994 under section five after his pro-gay rights group Outrage! staged a protest against the Islamist party Hizb ut-Tahrir - the law has created a "chilling effect" on free speech and the right to protest.
"In a free and democratic society, insults should not be a criminal offence," he says. "The law already protects people against discrimination, threats and incitement to violence."
Tatchell accepts, however, that repeal of the law would mean accepting behaviour widely regarded as repugnant.
In 2011 Emdadur Choudhury, a member of the extremist group Muslims Against Crusades, was found guilty under section five after he burned poppies on Remembrance Day as a two-minute silence was observed nearby by service personnel and their families. Choudhury also chanted slogans such as "British soldiers burn in hell".
Likewise, Tatchell accepts that repealing section five could open the door to displays like those of the Kansas-based Westboro Baptist Church, whose leaders are currently banned from entering the UK. The group has gained notoriety for picketing military funerals while brandishing lurid slogans condemning homosexuality.
Tatchell believes accepting such displays from a small minority is the price of liberty for all. "Freedom of speech is for everyone, including people we disagree with," he adds.
The law could be in line for reform. A Home Office review launched in October 2011 is examining whether the use of the word "insulting" in the law provides a "proportionate" response and a "necessary balance between the right to freedom of expression and the right of others to not be harassed, alarmed or distressed".
Indeed, in Scotland "threatening and abusive" behaviour is outlawed by Section 38 of the Criminal Justice and Licencing Act 2010 but insults are not. Under article nine of the Public Order (Northern Ireland) Order, a person accused of insulting behaviour is not guilty if he or she did not intend their conduct to be insulting and were not aware that it might be.
As it stands, anyone in England and Wales accused of a section five offence can defend it if they can demonstrate that their conduct was "reasonable".
For supporters of the current arrangements, it is not the law that is the problem but its interpretation by over-zealous officials.
Indeed, criminal barrister John Cooper QC argues that the fact none of the most prominent cases - such as those of the "gay" horse, the Scientology protester and the Christian landlords - resulted in convictions demonstrates that the legislation itself is sound.
"The issue is not what the law is, it's how it's interpreted, not just by the police but also by the Crown Prosecution Service," he says. "It's a matter of common sense. The statute is not meant to cover comments about the colour of one's shirt or one's hair."
Instead, he says, the prosecution must demonstrate that any insulting behaviour has caused undue distress.
For this reason, Cooper argues, the anti-section five lobby has failed to take account of the trauma that can be caused by the most aggressive insults.
"The people on this campaign are articulate, confident people who are robust enough to shrug off insults," he adds. "But it's not them the law is there to protect - it's there to protect vulnerable people.
"To some, a particularly vicious insult where there is also threatening behaviour is as damaging as a blow to the face."
Unsurprisingly, much of the debate around section five has been framed within the context of broader disputes about the impact and extent of political correctness.
Additionally, a series of high-profile cases involving the conduct of internet "trolls" has highlighted the shifting demarcation of where free speech ends and abusive behaviour begins.
However, for barrister-turned-comedian Clive Anderson - whose cynical barbs famously provoked the Bee Gees to storm off his chat show in 1996 - a much older legal tradition underlies the issue.
"This is not a modern thing," says Anderson, presenter of BBC Radio 4's legal affairs programme Unreliable Evidence. "For centuries people's religious beliefs have been protected by the blasphemy laws.
"In more modern times things like people's sexuality have become an area where we have tried to avoid causing offence. But where the two collide we have a problem - and we've discovered that we've taken on responsibility for standing between them."
Insults might always be a fact of life. The extent to which we tolerate them, however, is an age-old conundrum.