What matters most: free speech or public order? And how much of the former must we sacrifice to ensure the latter? This question has vexed our legislators for many years. In 1936, with Mosley's Blackshirts on the march in London's East End, a new Public Order Act criminalised behaviour that was not of itself violent but was "threatening, abusive, insulting or disorderly" and that was intended or likely to cause a breach of the peace.
The aim was to stop fascists screaming abuse at Jews in the streets; and while most civilised people wanted to shut the thugs up, there was a good deal of agonising over whether the wording was an unwarranted restriction of free speech, the beacon of liberty that marked us out from what was happening in Continental Europe at the time. On the other hand, the fear perpetrated by the Blackshirts was itself a threat to essential British liberties. A balance had to be struck and Parliament endeavoured to do so.
This debate was revisited 50 years later, when the Thatcher government updated public order laws in 1986 to take account of the disturbances in Brixton and Toxteth and at a succession of industrial disputes, such as the miners' strike and Wapping. Ministers also wanted to get a grip once and for all on the mayhem that had taken hold of our national sport. Every Saturday, the football terraces were a seething mass of contorted faces and vile chanting (so little change there, then). Crucially, section five of the Public Order Act 1986 removed the requirement for an intention to cause a breach of the peace. Instead, abusive or insulting behaviour was to be penalised if it was within the hearing or sight of a person "likely to be caused harassment, alarm or distress". This marked a further retreat from free speech. As one legal textbook put it, the criminal law had been "extended into areas of annoyance, disturbance and inconvenience".
Here we are, 25 years on, and once again this provision is proving controversial, not least because it is being used to criminalise what many people might consider simply to be a point of view that others do not like. Tomorrow, a parliamentary campaign is being launched in an effort to persuade the Government to remove the word "insulting" from the Act after a series of arrests and prosecutions of Christians for expressing their opinions.
They include a preacher who was convicted under section five for walking the streets of Bournemouth carrying a placard with the words "Stop Immorality, Stop Homosexuality, Stop Lesbianism". Another case involved Ben and Sharon Vogelenzang, Christian hoteliers in Liverpool charged with insulting a Muslim guest because they engaged in a conversation about religion. Mr Vogelenzang was alleged to have said that Mohammed was a warlord, while his wife stated that Muslim dress is a form of bondage for women. They were acquitted, but campaigners argue that they should never have been arrested in the first place and that people like them would be spared months of worry if the law was amended. Other notorious arrests under this measure include that of a teenager who described the Church of Scientology as a "cult" and the Oxford undergraduate who was arrested for asking a police officer if he realised his horse was gay.
Clearly, none of these "crimes" were envisaged as such in 1936, when a real menace stalked the land, or even in 1986, when the law was changed largely to stop abuse by football fans. The obvious problem is the subjective nature of an insult. While most of us can recognise abusive language when we hear it, in what way is it a crime to take issue with someone else's opinion, or even their religion? This is likely to become more problematic as the gay marriage debate heats up. This measure was not in the Queen's Speech, principally so that Her Majesty would not have to announce something opposed by the Church of which she is head. But when the consultation ends next month, the Government intends to legislate. As Lynne Featherstone, the Lib Dem equalities minister, said at the weekend, the consultation is not about whether to proceed, but how.
Christian groups are worried that antipathy to gay marriage will fall foul of the law. In this they are supported by Peter Tatchell, the human rights campaigner, who sees how such a law can easily be abused on grounds of political correctness. It is not so long ago that it would have been used to stop gay pride marches. Nor are these isolated matters. Figures unearthed by the Conservative MP Dominic Raab show that in 2009, section five of the Public Order Act was used more than 18,000 times, mainly for the non-specified crime of insult.
The Home Office has been consulting on this matter, but shows little inclination to do anything about it. If the debate around gay marriage is not to get ugly, the Government would be advised to change the law before people are hauled before the courts for defending their traditional understanding that matrimony, as the root of the word suggests, is the union of a man and a woman.
In a free and civilised country, people should not be abusive or gratuitously offensive to each other; but they should be entitled to voice an opinion that someone else might find insulting. It is a hallmark of liberty that it allows a person to say something that is provocative, otherwise it is no freedom at all. John Milton put it best: "Give me the liberty to know, to utter, and to argue freely according to conscience, above all liberties."