A woman who cannot be named has launched a legal battle for the right to "harvest" her seriously-ill partner's sperm so that she can have his children.
The High Court action is being seen as potentially an important test case, involving a man kept alive medically after a devastating series of heart attacks who could die at any time.
The woman "AB" says her partner "P" would have given his written consent had he known "he would be in his current state".
Her lawyers say she is P's common law wife and they have been in a relationship over several years and had extensive discussions about raising a family. Last year P proposed marriage with a ring, and she had accepted.
AB is challenging at London's High Court a decision of the Human Fertilisation and Embryology Authority (HFEA) preventing her partner's sperm being retrieved from him and stored for future use, possibly abroad.
High Court judge Mrs Justice Carr discharged a court order AB obtained in an emergency telephone application made to another judge on Christmas Eve allowing a hospital to carry out a harvesting operation pending the outcome of her judicial review application against the HFEA, the UK regulator that monitors the use and storage of human eggs, sperm or embryos.
Her legal challenge is due to be heard over two days next month.
AB's lawyers had argued the order was urgently needed because P was subject to a "do not resuscitate" (DNR) order and might die before the hearing, but Mrs Justice Carr ruled this week the order was legally flawed and should never have been made.
The judge also directed that the Family Division judge who hears AB's legal challenge should sit at the start of the hearing as a judge of the Court of Protection - a court set up to safeguard vulnerable people - to consider "what is in P's best interests" before going on to hear AB's arguments against the HFEA.
AB's lawyers told Mrs Justice Carr that P suffered his first cardiac arrest and was taken to intensive care in early December.
By Christmas Eve he had suffered four heart attacks and the DNR order had been issued. AB said she had been advised he was in a "permanent vegetative state" and could die at any moment.
The HFEA told AB's lawyers that there was no power to issue a special licence to allow the hospital caring for P to retrieve and store his sperm because of provisions of the 1990 Human Fertilisation and Embryology (HFE) Act requiring P's consent.
The HFEA also said P's hospital was not licensed to store gametes - the reproductive cells in sperm - and they should not be harvested "in circumstances where they cannot lawfully be stored".
Lawyers for AB are accusing the HFEA of misapplying the law when it decided it did not have power to grant a special licence for storage.
The latest medical update, received by the High Court this week stated that P's condition had stabilised and the DNR notice had been lifted. But it remained grave, and he relied on a tracheotomy for air and a nasogastric tube for feeding.
The judge refused to make a protective costs order in favour of AB to limit the amount she will be exposed to if she loses her legal challenge.
Her counsel Richard Alomo said she was "a person of very limited means". Her case raised important legal questions.
Mr Alomo said: "There is clearly a public interest in having this issue settled once and for all. She (AB) wants to obtain a decision she genuinely and sincerely believes her partner would want."
Rejecting the application, the judge said the case did raise a question of general public importance, but the information provided to the court about AB's assets and means was "wholly inadequate" to justify a protective costs order.
She said: "At least at some time P has been a wealthy man, having made a great deal of money from investment banking before retiring."