A judge could decide whether controversial changes to hospital services are lawful after health campaigners made an application to the High Court.
Lawyers are seeking a judicial review of plans for Calderdale and Huddersfield hospitals after safety fears were raised over longer journey times to A&E.
NHS bosses want to knock down Huddersfield Royal Infirmary (HRI) and replace the 400-bed hospital with a 64-bed site designed for planned NHS care.
Huddersfield would have an urgent care centre to treat people with minor ailments instead of a full emergency department.
Calderdale Royal Hospital (CRH) would be expanded with more beds and an A&E to serve both towns.
Law Firm Irwin Mitchell, acting for campaign group Hands off HRI, has applied for a judicial review of the way hospital bosses drew up the proposals.
Irwin Mitchell’s Yogi Amin said: “We believe that the Calderdale and Huddersfield NHS Foundation Trust has produced a flawed business case which does not present all the necessary evidence or follow the government guidelines.
“The effect of seeing through these plans could not only be millions of pounds of taxpayers’ money being used but also the closure of much-needed acute local NHS services.
“Local campaigners and professionals have argued that alternative local options based on the use of existing resources should have been considered, as opposed to the current proposed plan which would see hundreds of patients every month transported from the Huddersfield facility to CRH in Halifax.”
If the judicial review goes ahead it could potential see the hospital shake-up halted or altered.
The plans have already been referred to the secretary of state for health, Jeremy Hunt, by Calderdale and Kirklees joint health scrutiny committee.
The proposals were launched by Calderdale and Greater Huddersfield Clinical Commissioning Groups (CCGs) and a Full Business Case report was carried out by the hospital trust.
Owen Williams, chief executive of Calderdale and Huddersfield NHS Foundation Trust said: “The proposals in the trust’s Full Business Case have been developed following local consultation and are designed to secure sustainable healthcare services into the future for the people of Huddersfield and Calderdale.
“We respect the rights of local people and campaigners to use the judicial process and have received a copy of the proceedings. We will carefully consider our response in due course.”