A bid by hundreds of former soldiers to claim damages after they were exposed by the army to radiation during British nuclear weapons tests in the 1950s was rejected by the Supreme Court on Wednesday.
More than 1,000 veterans are seeking compensation and have been fighting through the courts for two years for permission to launch damages claims.
They blame their ill-health - including cancer, skin defects and fertility problems - on involvement in British nuclear tests in Australia, on Christmas Island and in the Pacific Ocean between 1952 and 1958.
The Ministry of Defence says it acknowledges a "debt of gratitude" but denies negligence.
Wednesday's judgement by Britain's highest court effectively blocks most claims though a certain number can still proceed under an earlier legal ruling.
Ten "lead" claimants won the first round of their battle in 2009 when a High Court judge said the claims could proceed.
But the MoD appealed that ruling and in 2010 the Court of Appeal blocked nine of the 10 claims, the judges ruling they were "statute-barred" as they had been filed too late.
And Supreme Court justices threw out the veterans' attempt to overturn that ruling by a four-to-three majority.
Lord Wilson ruled that the actions had "no real prospect of success."
He said: "Putting aside the law for one moment, all seven members of the court would wish to record their personal sympathy for the veterans.
"It must be bad enough for the nine veterans, and the other claimants, to learn that they have lost this final round, but to learn that they have lost by the narrowest possible margin must make it even worse."
If you appreciated this article then please consider donating to the Morning Star's Fighting Fund to ensure we can keep developing your paper.
Lord Feldman says that he didn't call grassroots Tories "mad swivel-eyed loons" while his accusers stand by their stories that he did.
As Aslef's annual assembly of delegates begins in Edinburgh tomorrow the general secretary explains the challenges his members - and workers across the country - face
France is the latest to face clamour from the EU to enforce crippling 'structural reforms.' The medicine is killing the patient