Ashton Kutcher and Demi Moore’s divorce settlement is edging closer and now we know there is no pre-nuptial agreement (unlike the Coen brothers film of the above name). Hollywood being what it is, the onetime highest grossing female actress is in the autumn of her career and Ashton is now the wealthy younger buck. Demi wants some of the financial action. After all she was the bigger Hollywood player when they got together and gave his career a leg-up.

This is one of those situations where a pre-nup, had it existed might have been crueller in the end to one party – to Demi Moore. Pre-nups try and cater for the future which is inherently uncertain. Ashton’s career has now overtaken Demi’s financially-speaking. Where agreements exist they should be updated every few years, like a Will.

For international families, young professionals, and high net worth individuals, pre-nups are actually a very good idea. But, there are pitfalls for couples surrounding pre-nups, even if the problems are a bit more prosaic than in the harsh world of Hollywood.

Such agreements are not considered binding in our divorce courts here, but can be persuasive and carry the day if they meet the formalities required when drawn up (including disclosure and independent advice on both sides). Also the agreement must not ignore the basic financial needs of the weaker party or of any children. Any agreement that fails to do that, can be partially or entirely ignored by a judge to provide for those needs.

International couples living here are often surprised to learn that the matrimonial regime from their home country will not be automatically followed here. They should draw up a fresh agreement, a “post-nup” if they want safer protection here.

Because of detailed changes to cross-border family law in the EU since 2011, there is also current uncertainty in how maintenance provision in a pre-nuptial agreement (i.e. beyond capital) would be enforced in certain countries. The law is bound to develop quickly in this area. Even so, and whatever changes the Law Commission may soon recommend, pre-nups will always remain planning documents that cannot always cater for every eventuality.