How 6 Drug Driving Cases Ended Up Being Dropped

A roadside swab that returns positive, or a laboratory result said to be "over the limit", may make a prosecution appear certain. That is not necessarily the case. Drug driving proceedings depend on a sequence of forensic and procedural stages: the roadside test, the taking of blood, laboratory testing and disclosure of the evidence to the defence. If one part of that process breaks down, the prosecution may fail before any verdict is reached.

Drug Driving Solicitors has acted for clients in dozens of drug driving matters resulting in discontinuance, dismissal or acquittal. Set out below are six genuine cases from the firm's own records, together with the precise issue that caused each prosecution to fail.

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

In Mr Lewis's case, the arresting officer stated in his witness statement that the roadside drug test had shown a "blue line" for cocaine. That is not the way a positive reading appears on that device, as a true positive result displays two red lines. Elsewhere, the officer's evidence was also internally inconsistent about the drug for which the test was allegedly 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, removing the legal basis for requiring a blood sample in the first place. No further evidence was offered.

Why it matters: roadside test readings, and the evidence recorded by the officers administering them, are open to challenge just like any other evidence. Differences in an officer's description of the test, including apparently minor discrepancies, may be sufficient to bring the case down.

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

Mr H provided part of his own blood specimen to an independent forensic toxicologist. The expert reached a clear conclusion: the available sample contained insufficient blood for a valid analysis to be undertaken.

After the Crown Prosecution Service received that opinion, alongside a formal defence statement, it discontinued the prosecution approximately a week before trial.

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

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 he informed police that he had a needle phobia. Where a person raises a potential medical reason for being unable to provide a sample, the law requires a medical professional to consider whether it amounts to a reasonable excuse. No medical professional was asked to make that assessment in his case.

An expert report, based on Mr Franklin's medical records and a consultation with him, verified that the phobia was genuine. In light of that evidence and its own procedural omission, the prosecution discontinued the case before trial.

Why it matters: a charge of "failure to provide" does not follow automatically. Police must ensure that a genuine medical reason is properly assessed. A failure to do so can weaken the prosecution's case entirely.

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

A number of the firm's matters depended on the same finding: the laboratory that had analysed the blood specimen no longer held UKAS accreditation to carry out the particular testing required by section 5A of the Road Traffic Act 1988. In Mr T's matter, this was discovered only after the prosecution served its own analytical data pack and it was examined.

Once the lost accreditation was identified, the reliability of the full analysis became questionable. The prosecution sought an adjournment on the trial date, but the court declined the request and no evidence was offered.

Why it matters: an "above the limit" reading has value only if the laboratory producing it was appropriately accredited for the test. Where that accreditation was absent, the figure in the report may be incapable of standing up in court.

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

After Mr Sharpe pleaded not guilty, 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 given at another hearing, but these were missed as well.

When the matter came before the court for a preliminary hearing only weeks before trial, the prosecution had still not complied. Rather than continue without properly ordered evidence, it discontinued the case.

Why it matters: the Criminal Procedure Rules impose genuine duties on the prosecution to disclose evidence within the required timeframe. Repeated non-compliance is not merely procedural. Courts have repeatedly prevented the prosecution from relying on evidence served too late, and that can prove fatal to a case.

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

Mr Singh's blood specimen returned a result below the legal limit, yet he was charged with the separate offence of driving while unfit through drugs. The allegation relied in part on statements he made during a police interview months later.

Professor Atholl Johnston was instructed as an expert and concluded that the concentration found in Mr Singh's blood did not align with what he had said he had taken. The level was also unlikely to have had much effect on him at all. Alongside a separate error in the hospital's paperwork, this led the prosecution to discontinue the matter.

Why it matters: the fact that a person has been charged does not establish that the evidence supports the allegation. A result below the limit, or expert examination of what a detected level would realistically mean for driving ability, may defeat a charge founded on less secure evidence than it initially appears.

The Shared Pattern

These six prosecutions did not end because police simply "changed their mind." Each failed for a distinct and demonstrable reason: evidence from an officer that did not withstand examination, an inadequate sample, a medical explanation left unassessed, an unaccredited laboratory, missed disclosure obligations or a result inconsistent with the charge. In every instance, the defence team needed to know precisely what to examine.

For anyone facing a drug driving allegation, the circumstances of the stop, the specimen and the evidence supporting the charge may carry considerably more weight than one number in a laboratory report. Obtaining advice from a specialist solicitor at an early stage provides the strongest opportunity to establish whether any of these issues may also affect the case.

This article provides general information only and is not legal advice. Every case depends on its individual facts.