Prenup ruling could erode sex equality

Britain's Supreme Court has ruled that prenuptial agreements should be taken into account when dividing up a divorcing couple's assets after finding in favour of a German heiress who had applied to protect her fortune from her ex-husband.

The test case, between Katrin Radmacher, a paper industry heiress with a fortune of more than £100m, and her French ex-husband Nicolas Granatino, represents the first time a prenuptial agreement has been enforced by a UK court, and could bring Britain into line with the US and European family law.

The couple married in 1998, when Granatino was earning a six-figure salary working as an investment banker for JP Morgan. They signed a prenup which stipulated that neither party should benefit financially if the marriage failed. Granatino claimed he did not at the time realise the full extent of Radmacher's wealth, nor did he seek legal advice or have the document translated from German before signing it.

After living for most of their married life together in Chelsea, the couple separated in 2006. In the meantime Granatino had left his lucrative investment banking job for a post as a biotechnology researcher at Oxford University which paid a mere £30,000 salary.

In 2008 Granatino was awarded £5m by the High Court in recognition that the prenup was "manifestly unfair" and would have left him with no financial support even if he found himself in difficulty.

That award was slashed last year to £1m with the Court of Appeal ruling that prenups ought to be taken into account. The Supreme Court judges upheld that ruling today by a majority of 8-1, saying that "it is natural to infer that parties entering into agreements will intend that effect be given to them".

However, courts would retain the power to overrule prenups if they are unfair.

Prenups have not suddenly become legally binding. After all, Granatino keeps his £1m-plus settlement, which under the prenup he should not have been entitled to, but some lawyers are still claiming the Supreme Court has crossed a line.

Brenda Long of the law firm Blandy & Blandy told the Guardian the ruling "means the judiciary has overstepped its prescribed role of interpreting law and actually created law instead".

But other lawyers are more concerned about the potential the ruling has to erode sexual equality - because in the vast majority of cases it will be a wealthy man, not woman, calling the shots.

Stephen Foster of Stewarts Law told the Daily Telegraph: "The Supreme Court has created a rich man's (or in the case of Mrs Radmacher, rich woman's) charter to drive a hard bargain prior to marriage." ·