After six hours of deliberations, the jury failed to reach a verdict on the damages action brought by the wife of the architect Sir Norman Foster and her daughter by a previous marriage, India Langmead.
The women had sued for false imprisonment and 'slander by conduct' - being marched through the airport concourse in full view of the public after arriving on a flight from Brussels.
Mr Justice Drake discharged the jury of seven women and five men after the foreman said: 'I think it unlikely we will reach a verdict of 10-2 either way.' Both sides must pay their own share of total legal costs estimated at more than pounds 200,000.
Lady Foster, of Battersea, south- west London, said as she left court: 'I am very sad, obviously. I am disappointed that the jury was not able to come to a unanimous decision because it is a matter of principle for us. We will ask for a retrial.'
She added later in a statement: 'We are aware of, and sensitive to, the difficulties faced by customs officers in performing their duties effectively, but they should not act in an unfair and arbitrary way.
'One of our principal motives in bringing this case has been to stand up for the rights of the general travelling public . . .
'One of our reasons for bringing the case was to establish a point of principle: that whoever we are, all of us in this country are entitled to be treated with courtesy and fairness by those with authority over us.'Reuse content