A mother who campaigned for a change in the rules over medicinal cannabis is seeking a judicial declaration that a GP can prescribe the treatment to her severely epileptic son.
Co Tyrone woman Charlotte Caldwell wants the law clarified amid fears her 13-year-old son Billy is about to run out of a privately-sourced treatment.
The case is expected to be heard at the High Court in Belfast later this month.
In November last year the rules were relaxed to allow some cannabis-derived medicines to be prescribed to patients in the UK by specialist doctors in limited circumstances.
It followed the high-profile case of Billy Caldwell, whose mother had cannabis oil she had brought back from Canada confiscated at London's Heathrow Airport.
The boy was then admitted to hospital after suffering seizures.
Despite the new guidelines, access to medication remains uncertain.
Mrs Caldwell has issued judicial review proceedings against the Health and Social Care Board over an alleged failure to take a decision on a Canadian-sourced treatment.
She is seeking a declaration that a Northern Ireland-based GP or clinician who is not on the specialist register can lawfully write prescriptions for cannabis-based medication under the direction of a consultant paediatrician with higher qualifications in epilepsy diagnosis and management.
Mrs Caldwell also wants an assurance from the court that she can lawfully administer the drug to her son.
Issues around the level of clinical data and evidence on the product's effectiveness are expected to feature.
Papers in the case set out that Billy is currently receiving a medication following a private prescription provided by a consultant in the UK.
They state that the supply is due to run out next month, with Mrs Caldwell unable to afford more.
"If Billy's medication expires without a replacement then, based on what happened when he landed at Heathrow on June 11, 2018 and his medication was confiscated, he will suffer a seizure within 12 hours," papers submitted by the family's legal representatives KRW Law contend.
"Further, it is dangerous for Billy to have a total withdrawal from his medication because it can cause serious side-effects."