The human rights group Liberty is threatening to sue the government and Crown Prosecution Service (CPS) over the bitterly contested law of joint enterprise, arguing that it is discredited and racist in the way the authorities pursue it. Under the law, people present when a person is killed can be convicted of murder despite not committing any serious violence themselves, if they are found to have “encouraged or assisted” the perpetrator. Liberty is acting for the campaign group Joint Enterprise Not Guilty By Association (Jengba), which supports approximately 1,400 people in prison who believe they have been unjustly convicted of serious crimes perpetrated by somebody else. Many joint enterprise prosecutions cast all participants in an incident as a gang, which ascribes to them a collective motive for an attack. There have long been accusations, supported by academic studies and parliamentary inquiries, that the gang label is attached disproportionately and without adequate evidence to black and minority-ethnic young men. The Guardian has reported extensively on the 2017 case in which seven black and mixed-race teenagers were convicted of murder, and four more of manslaughter, after the fatal stabbing in Moss Side, Manchester, of Abdul Hafidah, 18, by one of them. Greater Manchester police and the CPS portrayed all the young men as a gang who “controlled territory” but presented minimal evidence of criminal gang activity, and most of the defendants had no criminal records. Neither the Ministry of Justice (MoJ) nor the CPS records numbers of joint enterprise prosecutions, nor the defendants’ ethnicity or age, nor whether gang evidence was advanced in a case. Liberty argues that means the authorities are breaching their duties under the Equality Act because they are failing to “ascertain the extent of, and eliminate, any race discrimination in the use of joint enterprise laws”. In a letter sent to justice secretary Dominic Raab and director of public prosecutions Max Hill last month, Liberty called on the MoJ and the CPS to immediately begin recording and publishing such data, and “properly take into account” the duty to apply the joint enterprise law equally. Liberty threatened to issue a judicial review claim against both the MoJ and the CPS if they did not respond positively by Monday, 4 April. Both have asked for more time to respond. Lana Adamou, a lawyer at Liberty, said: “We all want our communities to be safe, and for our laws to treat us equally. But joint enterprise is overwhelmingly used against people from marginalised communities, especially young black men, and drags people unfairly into the criminal justice system. “It’s completely unacceptable that there is still no official data being recorded about how the doctrine is used and who it is used against. By failing to do so, the justice system has been recklessly sweeping thousands of young black men into the prison system.” Gloria Morrison, co-founder of Jengba, said that joint enterprise has been applied in a racist way to “over-criminalise” people, and described it as “common law, used against common people, that makes no common sense”. A CPS spokesperson said: “We have received a letter from Liberty regarding joint enterprise prosecutions and we will respond in due course.” An MoJ spokesperson said: “While charging decisions are made by independent prosecutors, we are currently considering the feasibility of collecting data on joint enterprise cases.”