Lawyers say a Supreme Court ruling on an estranged lesbian couple's dispute over their seven-year-old daughter will have implications in a number of areas.
Five Supreme Court justices analysed evidence at a hearing in London in December - following rulings by judges in the High Court and Court of Appeal - and are now due to publish a ruling.
One woman is the youngster's biological mother and sole legal parent, and the second woman considers herself a de facto parent, courts have heard.
Their relationship broke down in 2011, more than three years after the girl was conceived by IVF treatment and born.
Judges have been told the girl was taken to Pakistan by her biological mother in early 2014. The second woman then launched legal action and asked judges to order the youngster's return to the UK.
A High Court judge and Court of Appeal judges concluded they did not have the jurisdiction to make such an order because the girl was not habitually resident in the UK when legal proceedings were launched.
The second woman is now hoping the Supreme Court will rule in her favour.
Solicitor Pauline Fowler, a partner at Hughes Fowler Carruthers, says the case is the first of its kind and has given Supreme Court justices the chance to consider a number of issues.
John Darnton, a specialist family lawyer at law firm Bircham Dyson Bell, says the case highlights the problems of applying legal principle to reality in the modern world.
"Families now take a myriad of different forms and relations," he said. "This case illustrates the difficulty of trying to apply imperceptive legal principles to 'real-life' situations."
He added: "The position is complicated further when dealing with the international movement of children when no formal treaties are in place."
Judges have ruled that no-one involved can be identified in reports.
Mrs Justice Hogg initially analysed the case at a hearing in the Family Division of the High Court in 2014 and dismissed an application by the second woman.
A panel of judges - which included Sir James Munby, the head of the Family Division of the High Court - dismissed an appeal by the second woman after a hearing in the Court of Appeal last year.