A decision by the Supreme Court later in the divorce case of a German heiress could change the law on pre-nuptial agreements in England and Wales.
In July, the Court of Appeal agreed that Katrin Radmacher, thought to be worth £100m, should be protected by the terms of a German marriage contract.
But her ex-husband Nicolas Granatino is fighting to get that ruling overturned.
So-called “pre-nups” are not currently binding in England and Wales, but the outcome of the case could change that.
Ms Radmacher’s former husband had agreed not to make any claims on her fortune if they split up, but was awarded £5.85m by a High Court judge in 2008.
She challenged that decision and judges at the Court of Appeal agreed that the couple’s pre-nuptial contract should have been taken into account.
The Law Commission is due to report in 2012 on whether a change in the law should be made to ensure pre-nuptial agreements are fully enforceable.
Until then, the Supreme Court ruling will provide the clearest guide.