6 Drug Driving Cases Dropped by the Courts and What Led to It

A positive roadside swab or a laboratory result showing someone "over the limit" may make a prosecution seem like a foregone conclusion. It is not. Drug driving cases depend on a sequence of forensic and procedural steps, including the roadside test, collection of the blood sample, laboratory analysis, and disclosure of the evidence to the defence. If a significant problem arises at any stage, the prosecution can fall apart before a verdict is reached.

Drug Driving Solicitors has acted for clients in dozens of drug driving matters that concluded through discontinuance, dismissal, or acquittal. The following six examples come from the firm's own case history and illustrate the particular issue that caused each prosecution to fail.

1. The Officer's Account of the Roadside Test Fell Apart R v Lewis, Manchester Magistrates' Court [Case Dismissed, February 2023]

In Mr Lewis's case, the arresting officer stated that the roadside drug-testing device had displayed a "blue line" indicating cocaine. That description did not match the way the device actually records a positive result, which is shown by two red lines. Elsewhere in the same evidence, the officer also gave conflicting information about which drug had supposedly produced the positive result. These discrepancies were brought out during cross-examination at trial. The prosecution then accepted that it could no longer establish that the roadside test had been positive, undermining the legal basis on which the blood sample had been required. No further evidence was offered.

Why it matters: evidence from roadside testing, including an officer's record of what the device showed, is open to challenge just like other evidence. Contradictions or inaccuracies in the description of the test, even where they initially appear minor, can undermine the prosecution's case.

2. The Blood Result Was Below the Legal Limit R v Singh, Swindon Magistrates' Court [Case Discontinued, December 2022]

Mr Singh's case was unusual because analysis of his blood specimen showed a result below the legal limit. Despite this, he was prosecuted for the separate offence of driving while unfit through drugs, with the case relying in part on comments he had made during a police interview months later. Professor Atholl Johnston was instructed as an expert and concluded that the level detected in Mr Singh's blood did not correspond with the amount he had described taking and was unlikely to have had much effect on him. Together with a separate mistake in the hospital's paperwork, that expert evidence contributed to the prosecution ultimately discontinuing the case.

Why it matters: the fact that a charge has been brought does not necessarily mean the available evidence supports it. Where a result is below the legal limit, or expert analysis casts doubt on what the detected level would realistically mean for a person's ability to drive, a charge resting on weaker evidence may not survive detailed scrutiny.

3. A Medical Explanation Was Not Properly Considered R v Franklin, Cambridge Magistrates' Court [Case Discontinued, April 2022]

Mr Franklin faced a charge of failing to provide a specimen after informing the police that he suffered from a needle phobia. When a person raises a possible medical explanation for being unable to provide a sample, the law requires a medical professional to assess whether it amounts to a reasonable excuse. In Mr Franklin's case, no medical professional was brought in to carry out that assessment. An expert later reviewed his medical records, consulted with him, and confirmed that his needle phobia was genuine. In light of both that evidence and the earlier procedural failure, the prosecution discontinued the case before trial.

Why it matters: a charge of "failure to provide" does not automatically amount to an offence in every circumstance. Where there is a genuine medical reason, the police are required to have it properly assessed. Failure to do so can substantially weaken the prosecution.

4. The Laboratory Lost the Required Accreditation R v LT, Llandudno Magistrates' Court (March 2021)

A number of cases handled by the firm were affected by the discovery that the laboratory responsible for analysing blood samples had lost its UKAS accreditation for the particular testing required under section 5A of the Road Traffic Act 1988. In Mr T's case, the problem only became apparent after the prosecution served its own analytical data pack and that material was examined. Once it was established that the laboratory no longer held the necessary accreditation, the reliability of its analysis was called into question. On the trial date, the prosecution requested an adjournment, but the court refused the application and no evidence was offered.

Why it matters: a laboratory report stating that someone was "above the limit" depends on the reliability and proper accreditation of the laboratory that produced it. If the laboratory was not accredited to perform the relevant test, the reported result may not withstand scrutiny in court.

5. The Blood Sample Was Too Small for Valid Testing R v CH, Bexley Magistrates' Court [Case Discontinued, November 2020]

Mr H arranged for part of his own blood specimen to be examined by an independent forensic toxicologist. The expert reached a clear conclusion: the available quantity of blood was insufficient for a valid analysis to be performed. After that finding was presented to the Crown Prosecution Service together with a formal defence statement, the prosecution discontinued the case approximately a week before the scheduled trial.

Why it matters: strict requirements apply to the quantity, handling, and division of blood specimens. Having a defendant's own portion of the sample independently examined can reveal problems that were not identified by the prosecution's laboratory.

6. Repeated Disclosure Deadlines Were Missed Mr Sharpe [Case Discontinued, October 2018]

After Mr Sharpe pleaded not guilty, the court imposed a timetable requiring the prosecution to provide its forensic report and the supporting material. That deadline passed without compliance. Further directions were issued at another hearing, but those deadlines were missed as well. When the matter reached a preliminary hearing only a few weeks before trial, the required evidence had still not been disclosed. Rather than continue toward trial without its evidence properly in order, the prosecution discontinued the proceedings.

Why it matters: the Criminal Procedure Rules impose genuine duties on prosecutors to disclose evidence within the required timetable. Repeated non-compliance is more than a minor procedural issue. Courts have refused to allow prosecutors to rely on evidence served too late, and the absence of that evidence can prove fatal to a case.

The Pattern Behind These Cases

These six prosecutions did not end because the police simply "changed their mind." Each case involved an identifiable and demonstrable problem: evidence from an officer that could not withstand scrutiny, a blood result below the legal limit, a medical explanation that was not properly assessed, a laboratory without the required accreditation, an inadequate blood sample, or repeated failures to meet disclosure deadlines. In each instance, the outcome depended on a defence team identifying the precise weakness in the prosecution's evidence or procedure.

For anyone facing a drug driving allegation, the circumstances surrounding the stop, the collection and handling of the sample, and the evidence supporting the charge can be more significant than a single figure stated in a laboratory report. Consulting a specialist solicitor at an early stage can help determine whether similar forensic or procedural issues may be relevant to the case.

This article provides general information only and should not be treated as legal advice. The outcome of every case depends on its individual facts.