By Jon Silverman Legal affairs analyst

The only certain thing about court rulings on privacy is that there is no certainty.

How celebrities exploit the press could be a key issue

But some lawyers believe that Mr Justice Langley's decision to allow the News of the World to publish details about the Beckhams' private life "in the public interest" may have significant consequences for others in the public eye.

David Hooper, one of the UK's leading authorities on privacy and defamation, said: "This is a pretty dramatic change in the law and could have damaging implications for others, such as the Royal Family, who employ staff on contracts with confidentiality clauses.

"If something like a marital relationship is considered to be in the public interest, then it is quite a slippery slope. Where does it stop?"

In 2003, the Law Lords established that there is no "freestanding" right to privacy in English law.

Instead, those celebrities who go to the courts to protect their privacy - for example, Michael Douglas and Catherine Zeta Jones or, indeed, the Beckhams - have to bring their case under other types of action, such as breach of confidence.

'Brand Beckham'

And the developing law of confidence has tended to be in favour of the media where it can argue that publication is in the public interest.

For media lawyer, Mark Stephens, the key issue is how celebrities exploit the press for their own advancement.

"They're making a Faustian pact. David and Victoria have created 'Brand Beckham' which they desperately want to protect, but if the reality of their lives is at odds with the image, this latest judgement shows that a confidentiality agreement will not be an adequate shield."

This principle was set in a 1977 case involving the singer Tom Jones, who was also unsuccessful in an injunction to prevent revelations about his sexual behaviour.

Public mood

And in a landmark ruling in 2003, involving the footballer, Garry Flitcroft, the Lord Chief Justice, Lord Woolf, said that though public figures were entitled to a private life, they had less ground to object to media intrusion if they actively courted publicity.

Significantly, Lord Woolf said that it was for the person seeking the injunction to prove that interference with press freedom was in the public interest.

The unpredictability of privacy rulings contrasts with the public mood as reflected by a Guardian/ICM opinion poll exactly a year ago on the issue of David Beckham's alleged extra-marital relations.