Drug driving cases are being abandoned in Scotland due to a backlog of forensic cases.

Scotland’s traffic officers will have to bin hundreds of cases involving drug driving because they have been timed out.

The Scottish Police Authority is now investigating why 386 prosecutions have been abandoned after reaching the 12 month limit for prosecution.

It is reviewing “a serious failure” and has warned more cases are anticipated to reach the statutory limit.

SPA chairman Martyn Evans said “We are deeply concerned that 386 drug-driving cases cannot be progressed to prosecution due to testing and analysis not being processed within an adequate timeframe,” he said.

He added: “There is no doubt that demand for this service has been underestimated.”

Scotland introduced new legislation in 2019 making it an offence to drive while under the influence of certain drugs, including cocaine, morphine and cannabis.

The SPA said the level of offending had been under-estimated.

More than 5,600 drug-driving blood samples have been tested since the legislation came into effect.

The Forensic Services laboratory set up to support the change in the law has reported sustained volumes since 2020 – and the force is now prioritising cases of high harm or fatalities.

It’s a repeat of the problems experienced in England when forensic laboratories came under pressure in 2021 and 2018.

Last year, 21 forces revealed they had problems with lab testing results.

And in 2018, more than 40 cases were overturned and thousands more had to be reviewed after data was manipulated.

The problems were further increased when IT systems were hacked.

SPA said it will continue to work closely with Forensic Services, the Scottish Government, Police Scotland, the Crown Office and Procurator Fiscal Service and Her Majesty’s Inspectorate of Constabulary in Scotland (HMICS) to manage cases

Forensic Services has received £681,000 of additional investment from the Scottish Government to build its capacity by outsourcing 30% of cases to accredited commercial forensic science providers, with a further £370,000 committed this year.

Forensic Services director Fiona Douglas, commenting on the findings, said the situation is “deeply regrettable”, adding: “I want to apologise and reassure the public and our partners that our laboratory staff are working tirelessly and remain committed to processing samples in a timely manner.”

But the revelation comes at a time when the force is grappling with huge budget pressures.

Scottish Shadow Justice Secretary Jamie Greene said: “The SNP's police budget cuts need to be urgently reconsidered.

“Drug driving is an extremely dangerous crime so it is worrying that nearly 400 cases could not be prosecuted, in part due to a lack of police resources.”