Princess Caroline of Monaco won a landmark European Court Ruling in 2004 that appeared to ban publications from showing the children of celebrities when pictured with their parents in public but on private business.
But on Tuesday, Harry Potter author Rowling failed in a bid to ban publication of a photograph of one of her children which was taken in the street.
The picture, showing Rowling and her husband with son David in a buggy, was taken by a photographer from agency Big Pictures using a long-range lens, and appeared in the Sunday Express magazine.
The author brought the action under her real name, Joanne Murray, with her husband, Dr Neil Murray.
Mr Justice Patten said: ‘I have considerable sympathy for the claimant’s parents and anyone else who wishes to shield their children from intrusive media attention.
‘But the law does not in my judgment (as it stands) allow them to carve out a press-free zone for their children in respect of absolutely everything they choose to do.”
He granted the Murrays permission to appeal and continued a temporary ban on publication of the picture in the meantime.
David, now four, was 20 months old when the picture was taken, covertly, in an Edinburgh street in November 2004. His parents allege breach of confidence and privacy, and misuse of private information under human rights law and the Data Protection Act.
The judge said: ‘I think it is fair to say that it is seen by the claimant’s parents as something of a test case designed to establish the right of persons in the public eye to protection from intrusion into parts of their private or family life even when they consist of activities conducted in a public place.
‘If the law is such as to give every adult or child a legitimate expectation of not being photographed without consent on any occasion on which they are not, so to speak, on public business, then it will have created a right for most people to the protection of their image.
‘If a simple walk down the street qualifies for protection, then it is difficult to see what would not.”
The Big Pictures agency was awarded £40,000 interim costs against the Murrays, pending the outcome of the appeal and a final costs assessment.
Media lawyer Mark Stephens said: ‘It seems to me there is very little difference between the images of Dr Murray and his son and those in the Princess Caroline case. The British judges seem to be trying to put the bar in a different place.”