Civil liberty campaigners have warned that the prosecution of a woman for holding up a placard about the rights of jurors outside a court is part of the government’s increasing attacks on the right to protest. Liberty said the decision to prosecute Trudi Warner, 68, for contempt of court for sitting outside a London trial holding up a sign was “concerning”. Sam Grant, advocacy director of Liberty, called on ministers to reverse the restrictions on protest which are contained in recent legislation – in the Policing Act and Public order Act – and commit to protecting the right to protest. Grant said: “This decision is concerning – especially when seen in the wider context of increasing attacks on our right to protest. We all have the right to make our voices heard on issues that matter to us, but this government has continually narrowed our options for standing up for what we believe in. “As well as limits on how we can protest, we are also seeing the erosion of available defences for protesters, which has led to a situation where juries are the last line of defence for people facing imprisonment for protesting.” The decision to prosecute Warner was made by the government’s solicitor general, Michael Tomlinson KC, a minister and the Conservative MP for Mid Dorset and North Poole. It comes as police separately investigate at least 12 people on suspicion of attempting to pervert the course of justice for holding up similar signs outside a London court. Warner held up a sign outside Inner London crown court earlier this year spelling out the right of a jury to acquit a defendant on their conscience. She was referring to a famous sign in the Old Bailey celebrating the independence of jurors in the Bushel case in 1670, where a jury refused a judge’s direction to find defendants guilty. Warner held up a sign in March outside Inner London crown court, where a climate trial was taking place, which read: “Jurors: you have an absolute right to acquit a defendant according to your conscience.” She was protesting over restrictions on the defendants, imposed by the judge, which prevented them from mentioning climate change, insulation, fuel poverty or their motivations in their defence. Several people who ignored the judge’s restrictions have been jailed for contempt of court. Amy Pritchard and Giovanna Lewis, who were both jailed for seven weeks after they ignored the judge’s ruling not to mention climate change in their address to the jury, are appealing against their conviction for contempt of court. Warner was committed to the Old Bailey for contempt of court proceedings, where a high court judge referred the case to Tomlinson, to decide whether to pursue contempt proceedings or charge her with attempting to pervert the course of justice. He wrote to Warner last Thursday to say he had decided to prosecute her for contempt of court. As she faces a possible jail sentence, a separate investigation is ongoing into allegations of attempting to pervert the course of justice relating to at least 12 people who also stood outside Inner London crown court in May holding similar placards. The 12 have received letters from the Metropolitan police’s specialist public order unit that state: “You have recently been identified as taking part in an incident outside the Inner London crown court … whereby you were seated outside of the court and held a placard with the words; ‘The right of juries – to give their verdict according to their convictions’, in a place where both witnesses and jurors attending trials … could not avoid seeing them.” The letter went on: “This may amount to an offence under the common law of attempting to pervert the course of justice.” Tim Crosland, a lawyer and one of those being investigated by the Met, said: “It’s surreal. On the one hand it’s terrifying because that is the situation in this country at the moment, and on the other hand I feel like we are revealing something truthful about the situation, the extreme repression that is happening in this country at the moment in relation to people holding the government to account … and the repression that is happening in courts around trials for people exposing the government’s lies and how desperate the state is to prevent a jury reaching not guilty verdicts in these climate cases.” Scotland Yard said: “On Friday, 21 July the Met received an allegation of perverting the course of justice relating to activity outside of Inner London crown court on Monday 15 May. An investigation is being carried out; no arrests have been made.” A spokesperson for the attorney general’s office said: “Contempt of court is a serious matter and the power to issue proceedings is used sparingly. When investigating potential contempt issues, the law officers assess whether the evidential test for the specific form of contempt is met. “In this case, the law officers considered the deliberate act of doing something that interferes or creates a real risk of interference with the administration of justice, and whether it is in the public interest to begin proceedings for contempt. “We can confirm the solicitor general has determined to institute proceedings against Trudi Warner in the public interest, it will now be a matter for the court.”