A man interviewed by police over alleged transphobic tweets is challenging police guidance on hate incidents against transgender people.
Harry Miller, from Caistor in Lincolnshire, was contacted by Humberside Police over a limerick he re-tweeted.
He is now seeking a judicial review of the College of Policing (CoP) guidelines at the High Court.
The CoP said it would be "responding accordingly" to the legal action.
Mr Miller, a former police officer, said his legal challenge would argue that the guidelines undermined his freedom of expression under the European Convention on Human Rights.
He claimed the Humberside Police officer who interviewed him said "you've committed no crime, but we need to check your thinking".
He added that the police's intervention was a "chilling effect" on free speech.
"Any right-minded person has got to say 'now hold on a minute that's not on'," he said
"We're turning into a police state if that's where we're at and I'm resisting it".
In its guidelines, the CoP acknowledges that the police's approach to dealing with non-crime hate incidents "does not have universal support in society".
It adds: "While the police reject this view, it is important that officers do not overreact to non-crime incidents."
"To do so would leave the police service vulnerable to civil legal action or criticism in the media and this could undermine community confidence in policing."
The CoP said its guidelines were developed after concerns were raised by the Stephen Lawrence Inquiry that police forces were not properly recording hate incidents.
"Hate incidents can cause extreme distress and be the precursor to more serious actions or crime," it said.
"Not all incidents will escalate this way but it is only by recording concerns that police can assess their seriousness."