The Reasons Behind 6 Dropped Drug Driving Cases
A positive roadside swab or laboratory result that is "over the limit" may make a conviction seem inevitable. That is not the case. Drug driving prosecutions depend on a sequence of forensic and procedural stages: the roadside test, collection of the blood sample, laboratory testing and disclosure of the evidence to the defence. Where one part of that sequence breaks down, proceedings may fail before any verdict is reached.
Drug Driving Solicitors has acted for clients in dozens of drug driving matters that resulted in discontinuance, dismissal or acquittal. The following are six genuine examples from the firm's case history, each illustrating the particular issue that caused the prosecution to unravel.
1. The Officer's Evidence Could Not Be Relied Upon: R v Lewis, Manchester Magistrates' Court [Case Dismissed, February 2023]
In Mr Lewis's case, the arresting officer stated that the roadside drug test showed a "blue line" for cocaine. However, that is not how the device displays a positive result, as an actual positive result is shown by two red lines. Elsewhere, the officer's evidence was inconsistent about the drug for which the test was said to have been positive.
Those inconsistencies were brought out during cross-examination at trial. The prosecution then accepted that it could no longer prove the roadside test had been positive, removing the legal foundation for requiring a blood sample in the first place. No further evidence was offered.
Why it matters: roadside testing and the evidence recorded by officers are capable of challenge, just like any other evidence. Differences in an officer's description of the test, including points that may initially appear minor, can be sufficient to bring down the case.
2. The Laboratory Was No Longer Accredited During the Case: R v LT, Llandudno Magistrates' Court (March 2021)
A number of the firm's matters depended on the same finding: the laboratory that tested 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, the issue was identified only after the prosecution served its own analytical data pack, which was then reviewed.
Once it was confirmed that the accreditation had been lost, the reliability of the analysis as a whole was called into question. The prosecution sought an adjournment on the trial date, but the court declined that request and no evidence was offered.
Why it matters: an "above the limit" result has value only if the laboratory producing it was properly accredited for the relevant test. Without that accreditation, the figure recorded in the report may be incapable of standing up in court.
3. The Blood Sample Did Not Contain Enough Material for 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 sample did not contain enough blood for a valid analysis to be undertaken.
This conclusion was provided to the Crown Prosecution Service together with a formal defence statement. Around a week before trial, the prosecution discontinued the case.
Why it matters: strict rules govern the quantity, handling and division of blood samples. Testing a defendant's own portion independently may reveal defects that the prosecution's laboratory did not identify.
4. 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 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 that reason amounts to a reasonable excuse. In this case, no medical professional was brought in to make that assessment.
An expert report, based on Mr Franklin's medical records and a consultation with him, established that the phobia was genuine. In light of that evidence and its own procedural error, the prosecution discontinued the case before trial.
Why it matters: a "failure to provide" does not automatically amount to an offence. Police must ensure that a genuine medical reason is assessed correctly, and failing to do so may weaken the entire prosecution case.
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 deadline for the prosecution to disclose its forensic report and the supporting material. That deadline passed without compliance. At a subsequent hearing, further directions were given, but these were not followed either.
When the matter reached a preliminary hearing only weeks before trial, the prosecution had still not complied with the court's directions. Rather than continue without the evidence properly prepared, 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 a procedural point, as courts have repeatedly declined to permit reliance on evidence served too late, potentially ending the prosecution's case.
6. 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, yet he was charged with the separate offence of driving while unfit through drugs. The charge relied in part on statements he had made during a police interview months later.
Professor Atholl Johnston, instructed as an expert, concluded that the concentration identified in Mr Singh's blood was inconsistent with what he said he had taken and was unlikely to have affected him significantly. Alongside a separate error in the hospital's paperwork, this led the prosecution to discontinue the case.
Why it matters: a charge does not necessarily mean that the evidence supports it. A result below the limit, or expert examination of what a particular level would realistically mean for a person's ability to drive, may defeat a case founded on less secure evidence than it first seems.
What These Cases Have in Common
These six cases did not end because the police "changed their mind." Each was based on a distinct, provable defect: an unaccredited laboratory, a missed disclosure deadline, an inadequate sample, an unassessed medical explanation, a result inconsistent with the charge or evidence that failed under scrutiny. In every instance, the defence team needed to know precisely where to investigate.
For anyone facing a drug driving charge, the circumstances of the stop, the sample and the evidence supporting the allegation can be considerably more important than one figure in a laboratory report. Obtaining advice from a specialist solicitor at an early stage offers the best opportunity to establish whether any of these issues may also apply.
This article provides general information only and is not legal advice. Each case depends on its own facts.