A legal challenge has been launched after a "confusing and flawed" consultation into whether services should be moved away from an Oxfordshire hospital.
Cherwell District Council has applied for a judicial review into how Oxfordshire Clinical Commissioning Group (OCCG) carried out the survey.
It proposed moving some services away from Banbury's Horton General Hospital.
The OCCG said it has to tackle a predicted £200m funding gap by 2020-21.
Options put forward include moving stroke services and some critical care patients to the John Radcliffe in Oxford, although the Banbury hospital could see investment in other areas.
The Horton has been redesignated as a midwife-led unit due to a shortage of doctors until March, and the consultation suggests making the change permanent.
The challenge is made jointly with South Northamptonshire Council, Stratford-on-Avon District Council, and Banbury Town Council, and is supported by the Keep the Horton General campaign group.
The second phase of the consultation is expected to start in May and will look at accident and emergency, children's services and community hospitals.
Ian Davies, interim chief executive of Cherwell and South Northamptonshire Councils, said the two-part consultation "has proved incredibly confusing".
He added: "Those who will be most affected by any changes - namely the residents of Banbury and surrounding areas - are still unsure as to exactly what is happening to their local hospital.
"We consider it entirely unacceptable that the OCCG is trying to move ahead with plans which have not been fully understood by those who will suffer the consequences."
The councils must now wait to hear if the case will proceed to the High Court to be considered. A decision on this is expected next month.
OCCG spokesman Richard Mccrann said it had received the latter and "will respond appropriately".