Charges against five rail bosses accused of the manslaughter of four people who died in the Hatfield train disaster have been thrown out.
Four people died in the crash in October 2000
A corporate manslaughter charge against engineering firm Balfour Beatty was also dismissed by an Old Bailey judge.
But the five men, together with their employers, Balfour Beatty and Railtrack, replaced by Network Rail, still face health and safety charges.
Four people died in 2000 after a train derailed near the Hertfordshire town.
Five months into the trial, Mr Justice Mackay ordered the jury to find the men not guilty.
"It is not open to you to convict any of the six defendants on charges of manslaughter," he told the jury on Thursday morning.
He was not permitted to give reasons for his decision, he said.
"I must ask you to accept my ruling, which does not affect one way or the other the important decisions you will have to make when considering verdicts on the health and safety counts."
Three executives from Railtrack - which owned the East Coast Mainline at the time of the derailment - are among those on trial.
Alistair Cook, 50, Sean Fugill, 50, and Keith Lea, 53, all denied the manslaughter charges.
Two executives from Balfour Beatty - Anthony Walker, 46, and Nicholas Jeffries, 53, also denied manslaughter charges.
All five men, together with Balfour Beatty and Railtrack, also deny charges under the Health and Safety Act.
BBC correspondent Russel Hayes said the prosecution and defence in the trial were still "in the midst of immensely detailed evidence from both sides".
Prosecutors have alleged the crash was an accident waiting to happen.
When opening the case, prosecutor Richard Lissack QC said a faulty rail at the crash site had been identified 21 months before the crash and was left unrepaired.
He also said speed restrictions were not imposed in the area of the faulty rail and alleged that Balfour Beatty had been getting "seriously behind in remedying defects on the line".
Counsel for Balfour Beatty Ronald Thwaites QC said there was "no proper basis" for those allegations.
Jonathan Goldberg QC, for Jeffries, told the court it would be unfair to make the five men scapegoats in the "blame culture of modern-day Britain".
They had worked in an "under-funded, under-invested railway industry which had been neglected by governments... for over 40 years", he said.
The accident in Hatfield, on 17 October 2000, happened when the London to Leeds express came off the tracks at 115 mph.
It was derailed by a cracked section of rail leaving four dead and more than 100 injured.
Those who died in the accident were Steve Arthur, 46, from Pease Pottage, West Sussex; Peter Monkhouse, 50, of Headingley, Leeds; Leslie Gray, 43, of Tuxford, Nottingham; and Robert James Alcorn, 37, of Auckland, New Zealand.