A judge has given doctors permission to deceive a mentally-ill woman who is infected with HIV into taking drugs following a hearing in a specialist court.
Mr Justice Mostyn has concluded that treatment proposed is "plainly" in the woman's best interests but says evidence shows that she will be "exceedingly aggrieved" if she learns that she is being treated.
He has explained his decision in a written ruling following a private hearing in the Court of Protection, where judges consider issues relating to people who lack the mental capacity to make decisions, in London.
The judge said the woman, who was delusional and thought medics wanted to drink her blood, could not be identified.
He said doctors treating the woman had asked him to approve a planned treatment regime.
They proposed to administer medication "on a basis of deception".
Mr Justice Mostyn said the woman had not been suffering from a mental illness when she became infected nearly 20 years ago.
She had sought treatment and willingly been treated for nearly a decade.
But, following a "major deterioration" in her mental health, she had become "strongly opposed" to treatment.
Specialist had told how the woman was "in the grips of very powerful delusions" which prevented her from addressing many aspects of normal life rationally.
"She believes that she is a participant in a film about HIV, in which she will be participating with her husband," said Mr Justice Mostyn in his ruling.
"She does not, in fact, have a husband, but she believes that she is married to a celebrity sportsman.
"She believes that the person who is her husband will come back for her and take her away to live in connubial bliss.
"She believes that when blood samples are taken from her by the hospital staff it is done by them for the purposes of drinking her blood."
The judge added: "Above all, she is positive that she is not HIV infected, and were she to learn that she was being secretly and clandestinely administered with anti-retroviral treatment the evidence is that she would be exceedingly aggrieved."
Mr Justice Mostyn said he had placed "considerable weight" on the woman's "past wishes".
He went on: "I am wholly satisfied that the treatment proposed and the means of administration are plainly in (her) best interests."