It’s reassuring to think that there are principles that underpin our democracy in Britain, upheld by those who enforce the rule of law. The notion that we are innocent until proven guilty is sacrosanct for one – but for me as a journalist? The freedom of the press.

When I applied for press accreditation to attend the Labour party conference in June 2017, I assumed there’d be no issues. I pay my subs to the National Union of Journalists and have a press card, identification formally recognised by all police forces in the UK. I’m an active member of the Labour party and have interviewed its leadership on many occasions, in Westminster, at Glastonbury, or on the tube. I’ve also never been arrested, charged, convicted or cautioned for a criminal offence, and have reported from party conferences before.

Journalist sues police over 'leftwing extremist' claims Read more

For those who report and comment on politics for a living, the event is unmissable, and so I made preparations to attend. Months went by and I received no confirmation that I’d been accepted. There was no issue from the Labour party – I was told they were awaiting the police to sign off my security check. It was only on 20 September that I received an email informing me I hadn’t passed the police test. The Labour party told me all I could do was contact the police. I honestly thought it was just a mistake.

A sergeant told me bluntly the force would “not divulge the reasons” for this infringement of my civil liberties. My only right of recourse was to pay a fee to find out what information the police held on me through a subject access request.

This process takes up to 40 days, by that point the conference would long be over, and in any case it wouldn’t change their decision. Despite my best efforts to communicate directly with the force, this was the extent of what any officer would say to me. I felt I had little choice but to instruct solicitors to try to get some answers.

It has been an arduous (and expensive) process ever since, but on Wednesday, my case will finally be heard in a court of law. From institutional racism to deaths in custody, there are many graver examples of police forces in Britain needing to be held to account. But as the enforcers of the law, it’s vital that police actions are scrutinised and don’t go unchecked.

We are now a little closer to understanding what the police have been doing for years, but far from providing reassurance and answers, this legal process has unearthed some uncomfortable realities about the way the police conduct themselves.

They say by reporting on a story I indicate I think it is ‘acceptable', because I chose not to ‘intervene or walk away'

The police had long been using a secret policy to determine who they deemed fit to go to party conferences, with police intelligence (whatever that might mean) regarding an individual’s “mental illness”, “immigration offences”, “dishonesty” and “protests” all listed as possible reasons to refuse their right to attend.

This unpublished policy may well prove illegal: secret policies compromise fairness and transparency, which are crucial when upholding the rule of law.

My legal action has exposed something even more sinister: the rationale for refusing my access to this Labour party conference. The police have based their decision on the fact that while I was a student I engaged in peaceful protests, and secondly that I work as a journalist – it’s as simple as that.

Witness statements from the officers cite my time as a student campaigner as a reason to bar me: a time when I was elected as a student union officer and was voted on to the National Union of Students’ national executive council. The criminalisation of peaceful protest is all too common; I was dragged through a long and arduous ordeal when my vice-chancellor decided to boot five students (myself included) out of our university for being part of a peaceful political campaign. The university made defamatory allegations against me, and agreed to apologise as part of an out of court settlement. A statement was read out in court that set the record straight.

This attempt by the police to punish me sets a worrying precedent: engage in politics and peaceful activism as a student, and it’ll come back to haunt you one day.

The other reason cited for labelling me as an “extreme leftwing” activist is my journalism.

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The police force in question cite the coverage of a specific story, one that saw me report on a group of activists in the summer of 2016. I received a text message from an unknown source – a tipoff – and so I headed down to a central London location with a photographer, not entirely sure what to expect. In response to immigration raids at the Byron Burger chain, I watched as bugs were let loose by activists in one of their branches. I filed my story, and gave it little more thought. My reporting was picked up by the Guardian and ITV – this was a national news story, and I had broken it first.

The police are now saying my presence indicated I was “involved” in the action, an entirely baseless accusation. They say that by reporting on a story I indicate I think it is “acceptable”, because I chose not to “intervene or walk away”. This is not the first time police forces have treated journalists as extremists for doing their job.

A fundamental tenet of journalism is that we aren’t responsible for that which we report on, we are observers who document what we see. Access to exclusives or stories that might otherwise go unreported are dependant on sources, and the foundation of these relationships is trust. It would undermine press freedom if journalists were required to act as an arm of the state.

Labelling journalists extremists for carrying out their work is an affront to press freedom, and criminalising individuals for taking part in peaceful protests – as students or otherwise – must not be normalised in a functioning democracy. It shouldn’t take a court case to point that out.

• Michael Segalov is news editor at Huck magazine