The Ministry of Justice may have to fork out up to £750m if it loses a longstanding dispute over pension provision for fee-paid part-time judges. The estimated cost of providing additional pension entitlements to claimants is outlined in the department's annual report and accounts for 2017/18, published yesterday.

Pension entitlements are provided to salaried judges under the Judicial Pension Scheme. In 2005, Mr O'Brien, a retired fee-paid judge, brought an employment tribunal claim seeking retrospective parity of treatment with salaried judges by claiming pension entitlements under the Part Time Workers Regulations 2000. In 2013 the Supreme Court found O'Brien was entitled to a pension on terms equivalent to a comparable full-time judge and remitted the case to the employment tribunal to determine O'Brien's pension entitlement. Last year the Supreme Court referred a question in relation to the MoJ's liability pre-2000 to the Court of Justice of the European Union.

A CJEU hearing took place last month. Once a judgment is delivered, the case will return to the Supreme Court for a final judgment. The ministry says that should it lose the appeal, the combined cost is estimated to be up to £750m.

Meanwhile, the ministry said it is unable to measure any potential financial liability should it lose a separate appeal in relation to transitional pension arrangements for more than 200 judges, which the Employment Appeal Tribunal has ruled amounted to unlawful age discrimination.

The annual report also details the salaries of the department’s senior officials, which are a matter of public record. Permanent secretary Richard Heaton was paid the top salary of £180,000-£185,000. But the highest overall package over the year was paid to Susan Acland-Hood, chief executive of HM Courts & Tribunals Service. She received a total of £285,000-£290,000, comprising a salary of £125,000-£130,000 and pension-related benefits of £157,000.