A serviceman in his late 20s who suffered brain damage when assaulted might get specialist treatment at a clinic in Russia.
The man's mother has asked a judge in a specialist court to allow him to have stem-cell treatment not available in the UK.
Specialists caring for him in Britain are against the idea.
Mr Justice Baker has analysed evidence at hearings in the Court of Protection, where judges consider issues relating to people who do not have the mental capacity to make decisions, in London.
Lawyers representing the Ministry of Defence, which funds the man's care in the UK, have been at hearings and the judge has heard evidence from the man's mother and doctors.
The judge is expected to decide whether the proposed treatment is in the man's best interests in the near future.
He has ruled that the man cannot be identified.
Mr Justice Baker has been told that the man was injured during an incident four years ago.
He has heard that the man, who was not on active service at the time, had been left with a number of disabilities.
Doctors caring for the man say the treatment his mother wants is not licensed in the UK and will not be in his best interests.