The High Court must overturn Boris Johnson’s decision that Home Secretary Priti Patel did not breach government rules on behaviour, a union says.
The prime minister decided not to sack Ms Patel last year after a report found evidence of “bullying” and “some occasions of shouting and swearing”.
Mr Johnson backed Ms Patel, saying she had not broken the Ministerial Code.
The FDA union, which represents senior civil servants, said this reaction had “undermined” disciplinary procedures.
Home Office Permanent Secretary Sir Philip Rutnam resigned in February last year, saying he had been the target of a “vicious and orchestrated briefing campaign”.
He is pursuing an employment tribunal claim for constructive dismissal.
A report last November by Sir Alex Allan, the prime minister’s adviser on standards, said Ms Patel had “unintentionally” breached the Ministerial Code, governing conduct.
He found Ms Patel to be “action-orientated” and that she had felt “justifiably in many instances, frustrated by the Home Office leadership’s lack of responsiveness”.
Sir Alex added: “The evidence is that this has manifested itself in forceful expression, including some occasions of shouting and swearing. This may not be done intentionally to cause upset, but that has been the effect on some individuals.”
He resigned after Mr Johnson supported the home secretary, saying she retained his “full confidence”.
The FDA, of which Sir Philip is a member, is seeking a judicial review of the prime minister’s decision.
In a written submission, general secretary Dave Penman told the High Court that “civil servants should expect to work with ministers without fear of being bullied or harassed”.
Mr Johnson’s actions had “fundamentally undermined” the disciplinary process, he added, and the prime minister had “misinterpreted” the definition of bullying in the Ministerial Code.
Mr Penman said there was “bewilderment, dismay and anger among our membership” and there had been “serious detrimental effects to workplace relations and confidence in the process for dealing with complaints against ministers”.
He added that, if Mr Johnson’s decision was not “corrected” by the court, “his interpretation of the Ministerial Code will result in that document failing to protect workplace standards across government”.
In November, the home secretary apologised for any “upset” she had caused.
But she insisted the inquiry’s findings had made clear that “issues were not pointed out” to her in the course of the department’s “deeply challenging” work.
The prime minister has said he does not believe Ms Patel is a bully.