The recommendations of the Leng Review include changing PAs names to ‘physician assistants' and barring them from treating undiagnosed patients.

United Medical Associate Professionals (UMAPs) claims implementing the changes before the judicial review has concluded would pit GP surgeries and hospital trusts against their employees and will expose employers to tribunal claims.

The union further cites the 'negative impact' that the 'chaotic implementation' of the Leng Review has had on medical associates' mental health.

A hearing for the injunction is due to take place at the Royal Courts of Justice, with UMAPs represented by Sneha Nainwal of Shakespeare Martineau and Patrick Green KC of Henderson Chambers, who previously represented subpostmasters in the Horizon IT scandal.

UMAPs general secretary, Stephen Nash, said: ‘We are standing up for the rights of all PAs and AAs by no longer allowing our profession to be bullied by the medical establishment. The harm inflicted on medical associates, patients, and employers has gone on long enough.

‘We will also continue to support employers – many of whom have refused to implement the Leng recommendations and have financially supported our legal claims – by ensuring that highly trained medical associates continue to play a meaningful and effective role in the health service.'

In response, an NHS England spokesperson, said: ‘NHS England is committed to working with partners, including all members of general practice teams, and in line with all legal frameworks, for continued improvement in the quality of services and patient outcomes.'