Thank goodness for Mr Justice Julian Knowles. A judgement he delivered yesterday was a powerful defence of freedom of expression, which is expected to have significant implications.

Harry Miller, a 53-year-old man from Lincoln, had challenged the Hate Crime Operational Guidance of the College of Policing – the professional body which delivers training for all officers in England and Wales. Miller, himself a former police officer, had tweeted:

“I was assigned mammal at birth, but my orientation is fish. Don’t mis-species me.”

A complaint was made of “transphobia” which resulted in a visit from Humberside Police. Though no crime was committed, a “hate incident” was recorded.

Knowles said:

“There was not a shred of evidence that the Claimant was at risk of committing a criminal offence. The effect of the police turning up at his place of work because of his political opinions must not be underestimated. To do so would be to undervalue a cardinal democratic freedom. In this country we have never had a Cheka, a Gestapo or a Stasi. We have never lived in an Orwellian society.”

Evidence was presented to show that the underlying issue about gender identity is vigorously debated. Professor Kathleen Stock, Professor of Philosophy at Sussex University, stated:

“In my work, among other things I argue that there’s nothing wrong, either theoretically, linguistically, empirically, or politically, with the once-familiar idea that a woman is, definitionally, an adult human female. I also argue that the subjective notion of ‘gender identity’ is ill-conceived intrinsically, and a fortiori as a potential object of law or policy. In light of these and other views, I am intellectually ‘gender-critical’; that is, critical of the influential societal role of sex-based stereotypes, generally, including the role of stereotypes in informing the dogmatic and, in my view, false assertion that – quite literally – ‘trans women are women’. I am clear throughout my work that trans people are deserving of all human rights and dignity.”

Knowles quoted John Stuart Mill who wrote the treatise, On Liberty, which said:

“If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind.”

Adam Wagner, a human rights barrister, tweeted:

“To be clear: there should be a very bright line between speech which we as a society see as offensive, disgraceful, awful, hurtful – and speech which is punished by criminal law. As tempting as it is to lock up the people who offend and upset us it’s not generally a good idea and police are not good judges of where that line should be, if it is left vague.”

But can we rely on the judges either? Knowles is clearly a passionate believer in free speech. What if the matter had been left to another judge with a different view? Knowles declared that the police response in this case was unlawful. He did not say its guidance itself is unlawful. That guidance defines a hate incident as “any non-crime incident which is perceived, by the victim or any other person, to be motivated by a hostility or prejudice against a person who is transgender or perceived to be transgender”. Until the law is changed, that “chilling effect” on free speech will continue. Anyone can report anything as a “hate incident” – just notifying the police of their “perception”. Then if the police decide to record it as such – and a judge upholds them as doing so – this would seem to be a matter of discretion. Free speech should surely have a more secure basis than that. Gavin Williamson, the Education Secretary, is to be commended for seeking to protect open discussion in our colleges – but the threat goes much wider than academia.

It follows that reform of the judiciary remains an imperative – an area where the attention of the Policy Exchange is welcome. Pretty drastic change is also needed to the Crown Prosecution Service.

That makes the appointment this week of Suella Braverman as the Attorney General an encouraging sign. Last month she wrote on this site:

“Traditionally, Parliament made the law and judges applied it. But today, our courts exercise a form of political power. Questions that fell hitherto exclusively within the prerogative of elected Ministers have yielded to judicial activism: foreign policy, conduct of our armed forces abroad, application of international treaties and, of course, the decision to prorogue Parliament. Judicial review has exploded since the 1960s so that even the most intricate relations between the state and individual can be questioned by judges.”

So when we have all finished cheering Mr Justice Knowles, there is a lot of work to do. There must be public confidence that our legal system upholds freedom and democracy – rather than undermining that precious inheritance. To achieve that will be a huge challenge.