Ayla Cresswell had been in a relationship with Joshua Davies for about three years when he unexpectedly took his own life in August 2016.

The pair had shared their plans with their families and friends to get married and start a family.

In the hours following his death, and with the support of Mr Davies' parents, Ms Cresswell sought an urgent court order to remove his sperm.

She has paid for it to be stored at an IVF clinic ever since.

Brisbane Supreme Court Justice Sue Brown handed down her judgment on Wednesday where she ruled the order allowing the removal of the sperm was lawful.

She also agreed the way in which the tissue was harvested meant it could be deemed property and was satisfied the doctors did so on behalf of Ms Cresswell, meaning she was entitled to possess it.

Justice Brown had to take into account the wishes of Mr Davies in making her decision.

"There is clear evidence that Joshua Davies expressed a desire to have children," she said in her judgment.

But the judge said that was different to him consenting to Ms Cresswell using his sperm if he died.

"While Joshua Davies' family and friends believe he would support the decision of Ms Cresswell to make this application ... that is based on his express desires premised on them both being alive," she said.

Ultimately she found there was no evidence to suggest Mr Davies objected to Ms Cresswell using his sperm or that it would be contrary to his wishes.

Justice Brown said she was also satisfied the young woman's decision was not "an irrational response to grief".

"I am satisfied ... any child which may be conceived as a result of the use of Joshua Davies' sperm will be loved, cared for and able to be financially and emotionally supported, not only by Ms Cresswell but by the extended family," she said.

Ms Cresswell must provide the court with seven days' written notice about her intention to transfer and use the sperm.

It can only be used to produce an embryo that will be implanted in her.

Justice Brown said it was also up to the IVF clinic to decide if it was content to go ahead with the matter.

Queensland Law Society vice-president Bill Potts said the landmark decision for the state would have wide-reaching implications for family and successional law.

"Whilst I'm sure the applicant is overjoyed, and she has every right to be, this is an area which is ripe for legislation," he said outside court.

"We have to make sure that law keeps up with both the technology and the developing morality around this area."

Ms Cresswell did not comment outside court but barrister Kathryn McMillan QC said she was relieved.

Australian Associated Press