Drug Driving Cases Dropped: 6 Examples and the Reasons Behind Them

A positive roadside swab or laboratory reading "over the limit" may make a prosecution seem unavoidable. That is not necessarily the case. A drug driving prosecution depends on a sequence of forensic and procedural stages: the roadside test, the blood sample collection, laboratory testing and disclosure of the evidence to the defence. A failure at any stage can cause the prosecution to fail before a verdict is reached.

Drug Driving Solicitors has acted for clients in dozens of drug driving matters that resulted in discontinuance, dismissal or acquittal. Set out below are six genuine cases from the firm's case history, together with the particular issue that led to each case falling apart.

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 displayed a "blue line" for cocaine. That is not the way a positive result appears on that device, as a true positive result is shown by two red lines. Elsewhere, the officer's statement was also internally inconsistent about the drug for which the test had supposedly produced a positive result.

Those inconsistencies were brought out during cross-examination at trial. The prosecution then accepted that it could no longer establish that the roadside test was positive, removing the legal basis for requiring a blood sample in the first place. No further evidence was offered.

Why it matters: roadside test results, and the officers who document them, are open to challenge in the same way as other evidence. Contradictions in an officer's description of a test, including apparently minor discrepancies, may be sufficient to dismantle the prosecution's case.

2. 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 told 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 provides a reasonable excuse. No medical professional was brought in to make that assessment in his case.

An expert report based on his medical records and a consultation with him confirmed that the phobia was genuine. Confronted with both that evidence and its own procedural omission, the prosecution discontinued the case before trial.

Why it matters: a charge of "failure to provide" is not automatically made out. Police must arrange a proper assessment where there is a genuine medical reason, and failing to do so can weaken the entire prosecution.

3. The Prosecution Did Not Meet Its Disclosure Timetable: Mr Sharpe [Case Discontinued, October 2018]

After Mr Sharpe pleaded not guilty, the court imposed a specific timetable requiring the prosecution to disclose its forensic report and supporting material. The first deadline passed without compliance. At a later hearing, the court gave further directions, but those deadlines 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 proceed with its evidence out of order, it discontinued the case.

Why it matters: the Criminal Procedure Rules impose meaningful duties on the prosecution to disclose evidence within the required timescales. Repeated non-compliance is not merely a technical matter. Courts have repeatedly declined to permit reliance on evidence served too late, which may be fatal to the prosecution.

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

Mr H submitted part of his own blood specimen to an independent forensic toxicologist. The expert reached a clear conclusion: the sample did not contain enough blood to permit a valid analysis.

That opinion was provided to the Crown Prosecution Service together with a formal defence statement. Approximately a week before the trial date, the case was discontinued.

Why it matters: strict requirements apply to the amount, handling and division of a blood sample. Testing a person's own portion independently can reveal defects that were not identified by the prosecution's laboratory.

5. 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 that tested the blood sample had lost its UKAS accreditation to carry out the particular testing required under section 5A of the Road Traffic Act 1988. In Mr T's matter, this was identified only after the prosecution served its own analytical data pack and it was examined.

Once the absence of accreditation was established, the reliability of the complete analysis became questionable. The prosecution sought an adjournment on the trial date, but the court refused that request and no evidence was offered.

Why it matters: an "above the limit" reading is only reliable to the extent that the laboratory producing it was properly accredited. If the laboratory lacked accreditation for the relevant test, the reported figure may not withstand scrutiny in court.

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

Mr Singh's case was unusual because his blood specimen showed a level below the legal limit. Despite this, he was charged with 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, acting as an expert, concluded that the level found in Mr Singh's blood did not correspond with what he described having taken and was unlikely to have had much effect on him. Alongside a separate mistake in the hospital's paperwork, this led the prosecution to discontinue the case.

Why it matters: the fact that a charge has been brought does not establish that the evidence supports it. A below-limit reading, or expert analysis of what a particular level would realistically mean for a person's ability to drive, can undermine a charge founded on weaker evidence than it initially appears.

The Shared Pattern

These six cases did not end because police simply "changed their mind." Each involved a distinct and provable problem: an unaccredited laboratory, missed disclosure deadlines, an inadequate sample, an unexamined medical reason, a result inconsistent with the charge or evidence that did not withstand scrutiny. In every matter, the defence team had to know precisely where to investigate.

For anyone facing a drug driving charge, the circumstances of the stop, the sample and the evidence underpinning the allegation may be far more significant than one figure in a laboratory report. Obtaining advice from a specialist solicitor at an early stage offers the strongest opportunity to determine whether any of these issues may also arise in that case.

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