A high court judge has thrown out an attempt by the government’s most senior law officer to prosecute a woman for holding a placard on jury rights outside a climate trial. Mr Justice Saini said there was no basis for a prosecution of Trudi Warner, 69, for criminal contempt for holding a placard outside the trial of climate activists that informed jurors of their right to acquit a defendant based on their conscience. The judge accused government lawyers of “mischaracterising” the evidence when they said Warner had acted in an intimidating and abusive manner, confronting potential jurors outside the court and following them, in a deliberate attempt to interfere with the administration of justice. Warner, a retired social worker, was being pursued for contempt of court after a lone protest last year outside inner London crown court in which she held up a placard highlighting the right of jurors to acquit defendants on their conscience. She protested at the start of a trial of Insulate Britain protesters for a peaceful roadblock. But the attorney general decided to pursue Warner for contempt of court, and the solicitor general was in the high court last week to seek permission to charge her. In Monday’s ruling, Saini threw out the government lawyers’ application. He said: “The solicitor general’s case does not disclose a reasonable basis for committal … the conduct did not amount to an act of contempt. “I refuse the solicitor general permission to proceed and I dismiss the claim.” He challenged the solicitor general’s allegation that Warner had confronted, instructed, encouraged or incited potential jurors to ignore the judge’s directions when they came to their verdict. Saini said Warner had not harassed, impeded or even spoken to any of those entering inner London crown court last year, and criticised the government lawyers. “It is fanciful to suggest that Ms Warner’s behaviour falls into the category of contempt,” he said. “The category is limited to threatening, intimidatory, abusive conduct or other forms of harassment. “I reject the arguments made in the claimant’s … argument that Ms Warner confronted jurors … these submissions significantly mischaracterise the evidence.” Warner’s sign was in reference to a 1670 landmark case which cemented the independence of juries, known as “Bushel’s case”, in which a jury refused to find defendants guilty despite having been repeatedly instructed to do so by the judge. Warner’s placard read: “Jurors, you have an absolute right to acquit a defendant according to your conscience.” Warner, who waited for a year to find out if she would be prosecuted for contempt of court, said outside court she was feeling “very relieved”. “I feel it is job done,” she said. “What I was doing was drawing attention to the terrible repression of conscientious protectors, and in particular climate protesters, by the state. “If what I did will empower other defendants to use the power to acquit by juries, this will have been the fight of my life.” In his ruling, the judge said there was a well-established principle in law of jury equity; this was a de facto power to acquit a defendant regardless of directions from the judge. He said the principle in law had been tested in the highest courts in England and Wales, and existed in other countries such as Canada, New Zealand and the US. Warner stood outside inner London crown court last March for 30 minutes holding the placard as members of the public, lawyers and potential jurors filed into court. She held the sign on the first day of a trial for public nuisance of members of the climate campaign group Insulate Britain. The judge in that trial, Silas Reid, referred her action to the attorney general to consider contempt of court. Last week, the solicitor general argued in the high court that Warner should be prosecuted for contempt for holding the sign. Aidan Eardley KC told the court a prosecution was needed “to maintain public confidence” in the independence of the jury system and that if Warner went unpunished, similar acts were “likely to propagate”. He claimed Warner had confronted jurors outside court and her actions were an interference with the administration of justice. Saini said in his ruling on Monday Warner had made no attempt compel those going into the court. “What is striking to me is how little Ms Warner tries to engage with people, to get their attention, or to persuade them of anything. She was … in essence, a human billboard.” The decision was welcomed by supporters outside the high court. It came after the UN rapporteur on environmental defenders highlighted the repressive actions taken against climate campaigners in the UK. Michel Forst said he was alarmed at the restrictions being placed on defendants in climate trials, which include being prevented from mentioning the words climate change or fuel poverty, or the tradition of peaceful protests embodied in the US civil rights movement.