At a time when resources are scarce, the Merseyside Constabulary must have thought long and hard about its recent advertising campaign: a stern message to the people of the Wirral. ‘Being offensive,’ it declared, ‘is an offence.’ The slogan was put on a van along with text urging the public to inform on transgressors. Four officers posed beside it for a photograph, as if standing ready to enforce its orders. The police only recognised their error after a public outcry. ‘We would like to clarify,’ said Superintendent Martin Earl, ‘that “being offensive” is not in itself an offence.’

On its own, the incident is merely an embarrassment, but it represents a worrying general trend. Once it has been established as a principle that people can be arrested for what they say, not just what they do, then police may indeed believe that being offensive is an offence and act upon that belief.

Had the Merseyside police consulted the Crown Prosecution Service before unveiling the poster, they might have been reminded that hate crime is the exacerbated version of something that is already a criminal offence; that is to say, a crime that is ‘perceived’ to be ‘motivated by hostility or prejudice based on a person’s race or perceived race; religion or perceived religion; sexual orientation or perceived sexual orientation; disability or perceived disability and any crime motivated by hostility or prejudice against a person who is transgender or perceived to be transgender’.

So a ‘hate crime’ is only a crime if it would already qualify as a criminal offence without the aggravating factor. Yet it is disturbing how badly this is explained by the CPS. Many in the police — not just in Merseyside — think that someone who is insulted has been a victim of crime. Plenty believe it’s their job to scour social media looking for thought crime. Much as we might regret the coarseness of contemporary public debate, especially on Twitter, the creeping efforts to outlaw insults and offence are an infringement on basic freedoms.

The idea of making Islamophobia a criminal offence would serve the same purpose. Let us set aside the fact that people in Britain ought to be free to critique any organised religion. The notion of ‘Islamophobia’ was invented by Muslim hardliners to avoid scrutiny of their ideology, and the word is often deployed against moderate Muslims who stand up to the extremists. Sadiq Khan, the Muslim mayor of London, was once nominated by the Islamic Human Rights Commission as an ‘Islamophobe of the year’. If a law against Islamophobia were ever to pass, it would make life even harder for mainstream Muslims to challenge the hardliners who wish to speak for all of Islam.

The trouble with defending free speech — and the reason so few people are apparently prepared to do it — is that it requires speaking up for some pretty unpalatable individuals. Few readers of this magazine will share the sentiments of a tweet, allegedly sent by a Glaswegian called Joseph Kelly, saying unrepeatable things about Captain Sir Tom Moore after his death. The comments were idiotic, despicable — even hateful. But does that mean Kelly should be dragged through the courts? He already has been. He is facing trial in June under the Communications Act 2003.

The purpose of that act was supposed to deal with the likes of heavy-breathers and others who use telephones and computers to menace individuals. It did not foresee Twitter, which did not exist at the time. It is deeply worrying that the act should be used to prosecute people for making political statements. It is equally worrying that, rather than attempting to reverse this trend, politicians are making further efforts to criminalise speech.

David Cameron has reportedly joined forces with Tony Blair to make the case for outlawing the ‘glorification of terrorism’. Like censoring Gerry Adams in the 1980s, this is unlikely to be effective. The SNP’s Hate Crime Bill, which gives police far greater powers than Blair’s original legislation, is also worrying. The original draft could theoretically have led to J.K. Rowling being jailed for seven years for expressing her scorn at the term ‘people who menstruate’. There were plenty of activists who would gladly have seen her prosecuted had there been the legal means to do so. They may yet get their way.

In many areas of British public life, basic liberal values — the bedrock of our democracy — are under attack. There is a mood now to censor or to criminalise opponents, rather than to defeat arguments in open debate. When even the police are confused about what’s legal and what’s not, it’s time to clarify the law — and update the 2003 Act for the digital age.

Boris Johnson seems to feel guilty about scrutinising — or, as he now puts it, ‘abusing’ — public figures when he was a journalist. It’s odd to hear such language from someone who was until so recently such a fiery defender of the free press and British liberal values in general. As a journalist, he would frequently assail those who eroded — or did nothing to defend — these basic freedoms. It would be tragic if, as Prime Minister, he became part of the problem.