Daniel Hannan is a writer and columnist. He was a Conservative MEP from 1999 to 2020, and is now President of the Initiative for Free Trade.

Which of the following do you reckon constitutes a public order offence? Holding a demonstration in defiance of lockdown rules; vandalising a statue; recording an interview with a well-known Cambridge historian in which he makes a racist remark.

If you picked the third option, you could have a glittering career in the Metropolitan Police. London’s coppers, who switched from heavy-handed enforcement of the lockdown to indulgence of Leftist demonstrators, who literally dropped to their knees during violent protests, and one of whose commanders went so far as to issue a video asking BLM agitators to break the law considerately, has decided to investigate Darren Grimes over his interview with David Starkey.

Grimes, a Eurosceptic commentator, has been interviewed under caution in connection with Section 22 of the 1986 Public Order Act which makes the producer of a broadcast containing abusive or threatening language liable if “(a) he intends thereby to stir up racial hatred, or (b) having regard to all the circumstances racial hatred is likely to be stirred up thereby.

No one, as far as I can tell, has defended Starkey’s assertion that, had the transatlantic slave trade constituted a genocide, “there wouldn’t be so many damn blacks”. Indeed, the dyspeptic doctor himself has issued a (for him) exceptional apology.

We can all agree that his remarks were intemperate, inaccurate and impolite. More than that, they were racist – a word that has been cheapened through overuse, but which applies in this case. A racist remark, though, does not in itself constitute a crime. The test is whether anyone hearing it would be stirred to racial hatred. In this instance, it seems vanishingly improbable. The common reaction, as we have seen, was a shudder of distaste at the speaker.

There used to be a clearly understood distinction between opinion (“Why are there so many damn Archenlanders in Narnia?”) and incitement (“Are you just going to stand there and let these Archenlanders violate our Marshwiggles?”) But that distinction has been systematically demolished, partly through legislation, partly through judicial activism and partly through over-eager policing.

It seems highly unlikely that the action against Grimes will result in a prosecution, let alone a conviction. But that doesn’t make it OK. For one thing, every investigation of this kind diminishes civil liberties and undermines the police. For another, there is a human cost even in cases that don’t reach court. As Mark Steyn (himself a victim of frivolous and malicious hate crimes accusations) puts it, “the process is the punishment”.

Grimes spent the better part of four years fighting off vexatious charges brought by people who resented the outcome of the 2016 EU referendum. Although he was completely exonerated in the end, nothing could undo the stress, the financial cost and the damaging media reports. Now, he faces going through another such ordeal. And the poor chap is still only 27.

Hate crimes are one of the places where we hear screeching gears as our politico-legal class pulls one way and public opinion the other. It is incomprehensible to most people that a police force that claims to be overstretched and underfunded can find time to chase a young Geordie journalist (“investigate crimes, not Grimes”, as one wag put it).

There is also a strong suspicion of partiality. Had David Starkey made his remarks in, say, a Guardian interview, does anyone seriously imagine that that paper’s editor would find herself under investigation? Yet, as the public looks on in bewildered alarm, the Law Commission is plugging ahead with its attempts to extend hate crimes legislation even further – this time to include misogyny.

Labour MPs have piled in against Grimes. Karl Turner, a shadow law minister, came out with a singular definition of free speech when he declared: “Of course everyone has the right to freedom of expression. But that doesn’t mean freedom from the consequences from what they have said. As I understand it, the police are investigating complaints. And it is right that they should investigate racist behaviour.”

Got that? You have absolute freedom of expression, but you may end up getting your collar felt if you exercise it in the wrong way.

Keir Starmer agrees. “I think it does sometimes have to involve the police,” he said on Monday. “There has got to be a level of tolerance of course, but there is a line which can be crossed, and it’s very important that it is investigated, and that in some cases there are prosecutions.”

Starmer has what coppers call “previous” here. When he was Director of Public Prosecutions, he reportedly overruled his staff to insist on pushing ahead with a case against someone who had made a joke on Twitter about blowing up Robin Hood airport.

If Boris Johnson moves to reverse the spread in these illiberal laws, he will be in the happy position of having the electorate with him but Labour against him. That, though, is not why he should act. He should act because, until he does, there will be many more travesties: more wasted resources, more ruined lives, more tarnished liberty. “It’s a free country”, we used to tell one another. Let’s make it one.