Police inLondonhave been accused of abusing their powers to curb protest after research found that less than 3% of arrests for conspiracy to cause a public nuisance in the past five years resulted in a prosecution.
The research also found an almost tenfold rise in the number of arrests in the capital for the offence, most commonly used to target activists, since 2019 whenExtinction Rebellionset off a wave of climate activism.
Campaigners said the findings showed police misusing the law to shut down protest with a power that allowed them to intimidate protesters by placing them in pretrial custody, impose onerous bail conditions and collect their DNA and fingerprints.
But police said they had a duty to intervene “where protest crosses the line into criminality” and that the difference in the thresholds of evidence between arrest and charge explained the discrepancy found in the research.
Areeba Hamid, a co-executive director ofGreenpeaceUK, which carried out the research, said: “The fact that police are routinely dragging protesters off the streets for a crime they almost always fail to charge them with amounts to an abuse of their powers and an assault on the right to protest.
“Arresting law-abiding people because they’re politically inconvenient is a frightening development in any democracy and is a direct result of the government’s instinct to shut down free speech and prevent people standing up for issues they care deeply about.”
Broadly, the offence of conspiracy to cause a public nuisance involves a group of people agreeing to take part in an act that, whether it takes place or not, could cause serious harm, disruption, or obstruction to the public.
Since 2022, when the offence was placed on a statutory basis, it has carried a penalty of up to 10 years in prison. It is one of the most serious protest offences, and was used last year toconvict four Just Stop Oil activistswho were jailed for up to five years – the longest sentence ever for non-violent protest.
Greenpeace used freedom of information requests to find out how many people were arrested on suspicion of committing the offence each year between 2012 and March 2025. They found that between 2012 and 2018, 67 arrests were made, of which eight – or 12% – resulted in charges.
In 2019, the year that Extinction Rebellion and Fridays For Future brought hundreds of thousands of people to the streets in protest over climate breakdown, there was an increase in the use of the power, with 205 arrests that year alone. From then until March 2025 there were a total of 638 arrests under the power, of which just 18 – 2.8% – resulted in people going to court.
Raj Chada, a partner at the law firm Hodge Jones & Allen, who is one of the UK’s leading protest defence lawyers, said he was not surprised by the figures. “There was a massive growth in arrests for public nuisance in the latter days of XR … which were previously arrested for obstruction of the highway, and the vast majority of those cases never went anywhere.”
Chada said the offence, which then existed only under common law, gave police powers to arrest and detain protesters as well as to take DNA, fingerprints and photos – powers they did not have under more minor public order offences.
“It was a way for police control for demonstrations, because you could put bail conditions more easily on people to prevent them coming into central London, you could potentially put people into custody,” he said.
“You would put them on bail for several months, wait until the XR action was over, and then either no-further-action it or charge them with a more minor offence like obstruction of the highway.”
After a lull in protest activity during the Covid pandemic, arrests for conspiracy to cause a public nuisance increased again in 2021 with the Insulate Britain campaign.
Greenpeace’s data showed that in 2021 theMetropolitan policemade 272 arrests under the power, as protesters disrupted traffic on roads leading to the capital’s orbital motorway, the M25. No charges were laid that year.
The following year as part of a wider legislative crackdown against protest, the offence was placed on a statutory basis by thePolice, Crime Sentencing and Courts Act 2022, a change that Chada said made it easier for prosecutors to bring charges.
However, except for 12 cases the year the law was passed, including Roger Hallam and his fellowJust Stop Oilactivists handed severe sentences last year over their plot to block the M25, no one has been charged under the legislation since.
Tim Crosland, the director of Plan B, an environmental litigation charity, who campaigns on behalf of protesters facing prosecution, said: “The Greenpeace research confirms what we’ve witnessed directly these last few years. Part of the … crackdown on civil society is the deliberate inflation of grounds of arrest.
“This is both an intimidation tactic in itself and also unlocks powers of search and seizure under the Police and Criminal Evidence Act, enabling the police to seize phones and laptops and to conduct dawn raids on those exercising their democratic rights.”
The Met police said: “The threshold for arrest is reasonable suspicion that an offence has occurred. The threshold to charge someone is significantly higher, with officers needing to show that there is enough evidence to provide a realistic prospect of conviction at court. Proving that an individual has conspired with others to cause a public nuisance, to that standard, is particularly challenging. This is reflected in the limited number of charges for that offence.”