On 27 March 2023, Trudi Warner stood outside Inner London Crown Court, where a trial of four climate activists was in progress. She carried a placard that read: ‘Jurors: You have an absolute right to acquit a defendant according to your conscience.’ It did not instruct nor encourage any juror to acquit the defendants in the ongoing criminal proceedings. Rather, it summarised an essential common law principle: that juries have the power to acquit according to their conscience.

That principle, known as jury equity, has its origins in the Bushell’s Case (1670) 124 ER 1006, which established the right of a jury to find facts and apply the law to those facts according to its conscience without fear of judicial reprisal. The case arose when the recorder of London tried to compel a jury to convict two Quaker preachers for holding an unlawful assembly. The principle remains memorialised in a plaque at the Central Criminal Court, which provides that the case ‘established the right of juries to give their verdict according to their convictions’.

Despite that long-standing principle, the attorney general in the last government decided to commence contempt proceedings against Warner. Permission was refused by the High Court in April 2024 (HM Solicitor General v Warner [2024] EWHC 918 (KB)). Sani J remarked that it was ‘fanciful’ (para 36) to suggest that Warner’s behaviour amounted to contempt and that the attorney general had failed to recognise that ‘what her placard said outside the court reflects essentially what is regularly read on the Old Bailey plaque by jurors, and what our highest courts recognise as part of our constitutional landscape’ (para 42).

In spite of the strong judgment, the government initially sought to appeal it, but this was abandoned last month by the new attorney general.

It is welcome that Warner’s ordeal is over and that this long-standing principle has been affirmed. Its importance was summed up by Sir Patrick Devlin nearly 70 years ago:

Juries remain the light through which liberty shines. They may not be perfect – they do not always get things right and, indeed, at times reflect society’s ills, prejudices and wrongs – but they remain free to reflect a more general concept of what is fair and just.

There are many examples throughout history in which juries have performed that role. Clive Ponting was a high-flying civil servant who leaked details about how parliament had been misled over the sinking of an Argentinian ship, the General Belgrano, during the Falklands war. He was prosecuted under the Official Secrets Act 1911, but the jury acquitted him. Pat Pottle and Michael Randle stood trial in 1991 for helping double agent George Blake escape from prison in 1966 – they too were acquitted, despite their defences being ruled out. More recently, six of the Shell Seven were acquitted after damaging the oil and gas company’s London headquarters, despite the judge saying: ‘They don’t have any defence in law for the charges they face’ (‘Extinction Rebellion: jury acquits protesters despite judge’s direction‘, BBC News, 23 April 2021). Each case different, but each jury took its view about what justice required.

Of course, a judge’s directions still need to be followed and counsel in Warner agreed that participants cannot be lawfully invited in a trial to apply the principle of jury equity or even be informed of it. This is to resolve the tension between jury equity and the oath that jurors swear.

That leaves a slightly peculiar position whereby the principle of jury equity exits but jurors cannot be explicitly told about it in the trial. However, it still allows people like Warner to take part in protests outside the court and be ‘human placards’, informing all of this basic principle.

Is that enough, though? Isn’t it time for proper citizenship classes in school, explaining not only the basis of how our parliamentary system works, but also the fundamentals of our justice system? An informative and engaging court that covers justice would teach the principles of jury equity, judicial independence, and the burden of proof. It may even raise the standard of discussion about the state of justice in the UK more widely – now there’s a thought.