Six High Court judges are launching an unprecedented legal action against Justice Secretary Liz Truss.
The case marking a new low in relations between the Government and the judiciary will see the group accusing Ms Truss of unlawfully discriminating against them on grounds of their age.
Members of the group will also claim they have been discriminated against on grounds of sex and ethnic origin in the case, relating to a new judicial pension scheme.
It comes after Ms Truss faced heavy criticism for failing to defend three other High Court judges against attacks, following their decision to rule against the Government in a critical Brexit court case.
Under reforms introduced last year — before Ms Truss became Lord Chancellor — some serving judges are allowed to retain membership of an existing pension scheme, whereas others under a certain age, including the six bringing the case, were enrolled in a new scheme.
The claimants will argue they are being treated less favourably due to their age, while two members of the group will also say female judges and those from ethnic minorities are under-represented among those able to retain the more preferential pension terms.
Shah Qureshi, head of employment at Bindmans LLP, said: “We can confirm that we act for a small group of judges in relation to age, race and sex discrimination issues arising out of the new judicial pension scheme.
“As this matter is currently awaiting judicial determination we are unable to comment further.”
A two-week hearing, starting next week, has been arranged before a tribunal judge who is not affected by the new pension arrangements. There could then be further hearings before appeal judges.
The Independent contacted the Ministry of Justice which said it could not comment on ongoing litigation.
Last week the High Court ruled that Theresa May could not trigger Article 50 of the Lisbon Treaty, launching Brexit talks, without seeking Parliament’s approval. It lead to the three judges involved being attacked and branded “enemies of the people” in one newspaper.
Lord Chancellor Ms Truss was criticised for hesitating to leap to the judges’ defence, and then failing to address attacks strongly enough when she eventually issued a statement.