More than 40 people have had criminal convictions quashed following an investigation into alleged data tampering at a forensics lab, the National Police Chiefs' Council has said.
The NPCC's forensics lead, Chief Constable James Vaughan, said on Thursday the drug-driving prosecutions had been reversed following fresh testing.
So far some 2,700 cases have been re-analysed out more than 10,500 identified as potentially being affected by data manipulation at Randox Testing Services.
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Forty people who had either pleaded guilty or been convicted of drug-driving had their prosecutions overturned following the reanalysis, Mr Vaughan said.
One other had a conviction quashed at the Court of Appeal after a legal battle.
The officer added more than 50 further drug-driving investigations were dropped before prosecutions were won, with this number likely to rise.
The results of the investigation were described as a "national scandal" with a "devastating impact" by a lawyer seeking damages for 35 of the 40.
"People have lost their driving licences, and as a result lost their employment, struggled to pay bills such as mortgages and rents, and some have been unable to travel to see their families and children," added Andrew Petherbridge, of Hudgell Solicitors.
One of those is Luke Pearson, a scaffolder from Manchester who lost his job when he accepted a 12-month driving ban and a fine before having his case overturned in February, according to the firm.
"I think it is disgusting that this has been able to happen to so many people, and it was devastating to me," the 26-year-old said.
"It all put a strain on life, and on my relationship with my girlfriend as I was the main earner and we struggled with bills and rent.
"I was only an occasional, light cannabis user, but when the police tell you that science says you are guilty you can't argue."
The re-investigation of cases since 2014 was launched in January last year after allegations emerged that scientists had manipulated forensics data at an RTS site in Manchester.
Two men, aged 31 and 47, were arrested on suspicion of perverting the course of justice by Greater Manchester Police and have been bailed until January.
Six more people have been interviewed under police caution with one remaining under investigation.
The laboratory was used by 42 of the UK's 43 forces.