The recommendations of the Leng Review include changing PAs names to ‘physician assistants' and barring them from treating undiagnosed patients.
NHS England opposed the injunction bid and is also opposing the wider legal challenge.
Dismissing the application, Mr Justice Dove said he was 'unconvinced' that there was a 'justification' for a temporary injunction.
However, United Medical Associate Professionals (UMAPs) said the hearing was ‘nonetheless incredibly positive for medical associates'.
The union said that the proceedings ‘further clarified' that it is up to individual NHS employers to decide whether and how to implement the recommendations of the Leng Review. It also specified that employers must exercise discretion, consult UMAPs, and ensure any decisions they make are lawful and not in breach of employment and other laws.
UMAPs said: ‘We strongly urge all NHS trusts and primary care networks to await the outcome of our upcoming judicial review before making any changes to medical associates' job roles, as we know many are doing already.
‘Any employer that hastily presses ahead with implementing the recommendations while the judicial review is pending will face legal action from UMAPs. This will be emphasised by NHS England in an upcoming FAQ document.
‘In his summary remarks, Mr Justice Dove made clear that injunctive relief could not be granted without examining the lawfulness of the Leng Review itself. We are now adding Professor Gillian Leng as a third defendant to our judicial review case, which is being expedited. This is a welcome development that will allow us to directly challenge the legality of the Leng Review itself and finally deal with this matter in its entirety.'
The court also directed that UMAPS will have the right to reply to the response put forward by all other parties in the judicial review, which will allow UMAPS an opportunity to effectively address evidence put forward by the defendants.
The union added: ‘UMAPs continues to stand up for PAs and AAs across the country who are being dismissed or unfairly treated because of the Leng Review, including assistance at employment tribunals where necessary.
‘Our fight goes on, and we look forward to the judicial review proceedings.'