A scandal over sexual abuse in the submarine service has deepened as it emerged that eight in 10 rape charges tried by a military court martial over the past three years ended without conviction. The service justice system heard 53 charges of rape between 2019 and 2021, of which just 11 ended in guilty charges, according to Ministry of Defence figures. In relation to the total of 324 charges for all sexual offences brought before courts martial over the three-year period, 141 convictions were secured – a 43% conviction rate. Within the Royal Navy, 62 sexual offence charges were heard at a court martial over the three-year period, including rape, sexual assault and voyeurism, of which just 33 ended in conviction – a prosecution success rate of 53%. Last week, the head of the Royal Navy, Adm Sir Ben Key, ordered an investigation into “abhorrent” allegations in the submarine service in response to harrowing testimony from whistleblowers. Claims of physical and mental abuse included that a “crush depth rape list” had been compiled by male submariners, in which women were ranked in the order they should be raped in the event of a catastrophic event. The claims have raised grave questions about the culture and level of accountability of those serving in the armed forces. Before 2006, service personnel who committed the crimes of murder, manslaughter or rape in the UK had their cases dealt with in civilian courts. The law was changed to enable the military police to investigate past offences that had taken place abroad given that civilian authorities did not have jurisdiction. Critics claim there has been mission creep. Currently, decisions over where such serious cases are heard are taken on a case-by-case basis, with the service justice system normally hearing those where both the perpetrator and victim of a sexual offence are serving personnel. Within the three-year period covered by the latest data release, 71% of service police investigations were into alleged crimes that had taken place in the UK. There have been repeated calls for this to end. A review led by Judge Shaun Lyons recommended in 2018 and 2019 that rape and sexual assault with penetration committed in the UK should no longer be heard in the courts martial at all, except when the consent of the attorney general is given. A report last year from the Commons defence select committee, then chaired by the Tory MP Sarah Atherton, further urged the Ministry of Defence to remove cases of rape and sexual assault from military courts. Atherton wrote of conviction rates in military courts that were “four to six times lower than in civilian courts”. The latest data from the Crown Prosecution Service shows the conviction rate for rape charges in civilian courts is about 68%. The Lyons review had warned against comparisons between the two services given the higher volume of cases in the civilian justice system, as well as the profile of the cases. The Ministry of Defence has said that a comparison could not be made as the threshold for a case to be tried in a military court is lower than that in a civilian court. However, while giving evidence to the armed forces bill committee last year, the Centre for Military Justice, an independent provider of legal advice to serving personnel, emphasised that there remained evidence of worse outcomes of rape and sexual assault cases heard at courts martial than those at the crown court. John Healey, the shadow defence secretary, said his Conservative counterpart, Ben Wallace, appeared “increasingly isolated” in refusing to accept the case for reform. He said: “Trying the most serious offences in civilian courts would help improve investigations and raise conviction rates. Labour has challenged ministers to make the change. Modernising the courts martial system is long overdue. “Our plan builds on the government’s own judge-led review, the recommendations of the defence committee and calls from service personnel and their families.” A Ministry of Defence spokesperson said: “It is misleading to compare the civilian and military justice systems, because of the huge difference between the size of the UK population and the much smaller armed forces. A tiny variation in military case numbers hugely impacts on percentages. “That being said, in the service justice system a far higher proportion of cases proceed to trial, and convictions secured in the service justice system are greater than those in the criminal justice system, when looking at them as a proportion of allegations made to the police.”