A drug-driving case has been dropped following a review of blood test data from a forensics laboratory at the centre of a police investigation.
Samples taken from the 26-year-old Chester man were analysed by Randox Testing Services (RTS) in Manchester.
Two employees at RTS were previously arrested over claims data may have been manipulated.
The Crown Prosecution Service (CPS) said there was too little evidence for a realistic prospect of conviction.
RTS is used by police forces across the UK to analyse toxicology samples used in prosecutions.
According to police, 484 cases handled by the firm since November 2015 may have been affected.
A spokesman said: "We are working with the Home Office, police and the Office of the Forensic Science Regulator to assess the impact of the testing failure at Randox Testing Services.
"This includes establishing which cases have been affected by this issue and working with other agencies to decide what action should be taken in relation to those cases."
The two arrested employees, aged 47 and 31, were quizzed on suspicion of perverting the course of justice and have been bailed, police said.
The company, based in Northern Ireland, said the investigation centres on the "manipulation of quality control data, which supports test results".
The allegations relate to drug tests analysed at the Manchester office.
- 19 February 2017