A High Court judge is preparing to deliver a ruling on a staffing contract row between junior doctors and Health Secretary Jeremy Hunt.
Junior doctors have complained that Mr Hunt wrongly imposed the contract on NHS employers.
Justice for Health, a group founded by five junior doctors, says Mr Hunt acted beyond the scope of his powers by compelling NHS employers to adopt the new contract.
Mr Hunt says the complaint is without substance and should be dismissed.
Mr Justice Green, who analysed evidence at a High Court hearing in London last week, is scheduled to deliver a ruling on Wednesday.
Justice for Health, founded by Dr Nadia Masood, Dr Ben White, Dr Fran Silman, Dr Amar Mashru and Dr Marie-Estella McVeigh, says Mr Hunt's decision to impose the contract lacked a sound or rational foundation and should be quashed.
Mr Hunt says he approved a new contract but has not imposed it on employers or compelled them to adopt it.
The litigation follows opposition to Mr Hunt's plans for seven-day NHS services in England.
Junior doctors began strikes, the longest of which has lasted two days, in January.
The British Medical Association, which represents doctors, has suspended industrial action by junior doctors planned for October, November and December.