The death of an airman at Porton Down laboratories following secret nerve gas tests 50 years ago was "an accident waiting to happen", an inquest heard.
LAC Maddison was given 200mg of sarin
The jury in Trowbridge heard how days before Ronald Maddison's death on 6 May 1953, two other volunteers had suffered adverse reactions to the sarin.
Toxicologist Prof Robert Forrest told the ongoing case the human experiments should have been immediately stopped.
Ronald Maddison's family has campaigned to find out what happened to him.
The lawyer for Wiltshire Constabulary, Simon McKay, drew a comparison with the experiments to the use of "crash-test dummies" in collision labs.
"During the course of these experiments, the brakes had failed. Is that a fair analogy?" he asked Prof Forrest, who agreed.
Despite what happened to volunteers John Kelly and Oliver Slater, the scientists continued testing on humans regardless of their "near misses", Mr McKay told the inquest.
"No reasonable or conscientious scientist could not have realised that they were embarking into a dangerous area that would result in a loss of life," said Mr McKay.
He said the test had been a profound and "reprehensible failure".
The inquest, which started in May this year, had already heard how sarin doses had been gradually increased during the experiments.
LAC Maddison was given 200mg of sarin. He collapsed and died within minutes of having drops of sarin liquid put onto his arm.