6 Drug Driving Cases That Were Dropped and the Reasons Why

A roadside swab that is positive, or a laboratory result recorded as "over the limit", can make a prosecution appear inevitable. However, that is not necessarily the position. A drug driving case depends on a sequence of forensic and procedural stages, including the roadside test, blood sampling, laboratory testing and disclosure of evidence to the defence. If a failure occurs at any stage, proceedings may end before a verdict is reached.

Drug Driving Solicitors has acted for clients in dozens of drug driving matters resulting in discontinuance, dismissal or acquittal. The six examples below are drawn from the firm's case history and explain the particular reason each prosecution failed.

1. The Officer's Evidence Could Not Be Sustained: R v Lewis, Manchester Magistrates' Court [Case Dismissed, February 2023]

In Mr Lewis's case, the arresting officer stated that the roadside drug test had shown a "blue line" for cocaine. That is not how a positive result appears on the device, as a true positive displays two red lines. Elsewhere, the officer's statement was also inconsistent about the drug for which the test was said to be positive.

These contradictions 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. This removed the legal foundation for requiring a blood sample in the first place, and no further evidence was offered.

Why it matters: roadside test outcomes, and the accounts given by officers who record them, can be challenged in the same way as any other evidence. Discrepancies in an officer's description of the test, including apparently minor ones, may be sufficient to bring the case down.

2. An Inadequate Blood Sample Could Not Be Analysed: 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 sample contained insufficient blood for a valid analysis to be completed.

The Crown Prosecution Service was provided with that conclusion and a formal defence statement. Approximately a week before the trial, the prosecution discontinued the proceedings.

Why it matters: strict requirements govern the quantity, handling and division of blood samples. Testing an individual's own portion independently can reveal issues that the prosecution laboratory did not identify.

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

Mr Singh's case was unusual because his blood specimen was below the legal limit. He nevertheless faced a charge for the separate offence of driving while unfit through drugs, based in part on statements he made during a police interview months later.

Professor Atholl Johnston was instructed as an expert and concluded that the blood level did not accord with what Mr Singh had described taking. The professor also found that the level was unlikely to have had much effect on him at all. Alongside a separate mistake in the hospital's paperwork, this evidence led the prosecution to discontinue the case.

Why it matters: a charge does not itself establish that the available evidence supports it. A result under the limit, or expert examination of what a particular level could realistically mean for a person's driving ability, can defeat a charge that initially appears stronger than it is.

4. The Laboratory Had Lost Its Accreditation During the Case: R v LT, Llandudno Magistrates' Court (March 2021)

A number of the firm's cases depended on the same finding: the laboratory responsible for analysing the blood sample had lost its UKAS accreditation to carry out the particular tests required under section 5A of the Road Traffic Act 1988. For Mr T, this issue emerged only once the prosecution served its own analytical data pack and it was reviewed.

After the loss of accreditation was confirmed, the reliability of the full analysis became questionable. On the day of trial, the prosecution sought an adjournment. The court declined the request, and no evidence was offered.

Why it matters: an "above the limit" reading is only as reliable as the laboratory that generated it. Where the laboratory did not hold the necessary accreditation to perform the test, the figure in its report may not withstand scrutiny in court.

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

Mr Franklin was charged with failing to provide a specimen after informing police that he had a needle phobia. Once a person raises a possible medical reason for being unable to provide a sample, the law requires a medical professional to assess whether that explanation amounts to a reasonable excuse.

No medical professional was asked to make that assessment in Mr Franklin's case. An expert report, based on his medical records and a consultation with him, confirmed that the phobia was genuine. In light of that evidence and its own procedural failing, the prosecution discontinued the matter before trial.

Why it matters: a "failure to provide" does not automatically amount to an offence. Where there is a genuine medical reason, police must arrange for it to be assessed properly. Failure to do so may undermine the entire prosecution.

6. The Prosecution Failed to Meet Its Disclosure Timetable: Mr Sharpe [Case Discontinued, October 2018]

After Mr Sharpe entered a not guilty plea, the court imposed a clear schedule requiring the prosecution to disclose its forensic report and the underlying material. The first deadline passed without compliance. Further directions were made at a later hearing, but those requirements were missed as well.

When the case reached a preliminary hearing only weeks before trial, the prosecution had still not complied. Rather than continue without the evidence properly organised, it discontinued the proceedings.

Why it matters: the Criminal Procedure Rules impose meaningful duties on the prosecution to disclose evidence within the required timeframe. Repeated non-compliance is not merely technical. Courts have repeatedly prevented the prosecution from relying on evidence served too late, which may prove fatal to its case.

What Connects These Cases

These six prosecutions did not end because the police simply "changed their mind." Each failed for a distinct and demonstrable reason: evidence from an officer that did not withstand scrutiny, too little blood for testing, a result inconsistent with the charge, an unaccredited laboratory, an unexamined medical reason or missed disclosure obligations. In every example, a defence team needed to know precisely where to investigate.

For anyone facing a drug driving allegation, the details surrounding the stop, the sample and the evidence supporting the charge may carry much more significance than one figure on a laboratory report. Early advice from a specialist solicitor offers the strongest opportunity to establish whether any of these issues may also arise in the individual case.

This material is provided for general information and is not legal advice. Each case depends on its own facts.