The Law Lords should set guidelines on the division of assets in high value divorce cases, a leading barrister has claimed.
Melissa Miller was awarded a £5m settlement
James Turner QC is acting for Alan Miller, a millionaire fund manager ordered to hand over £5m to his ex-wife after less than four years of marriage.
Allowing courts to use their discretion had led to arbitrary rulings, he said.
The case is expected to result in a clarification of matrimonial law in "big money" cases.
In another case being heard by the Law Lords, Julia McFarlane is appealing against a ruling that her £250,000-a-year maintenance should run for a limited number of years.
Trauma of divorce
This would require her to save some of it to provide a lump sum for a clean break settlement.
Opening his case, James Turner QC, representing Mr Miller, said the McFarlane divorce raised "entirely different" issues.
He said there were three children involved in the McFarlane's long marriage and she had "sacrificed" her own high-flying career to care for them.
Their wealth had been "built up from scratch" while the Miller marriage had not only been short and childless, but all the wealth was brought in by Mr Miller, he said.
Mr Turner said that at the moment it was impossible to work out how the award figures were fixed by the courts.
The total settlement of £5m had been made without any explanation and without justification to the parties, he said.
Mr Turner said the parties should know the basis of how their case was decided because the courts should not impose more "trauma" on couples already suffering the pains of divorce.
The Law Lords are expected to continue hearing evidence for four days.