6 Drug Driving Cases That Were Discontinued and the Reasons Why

Receiving a positive roadside swab or a laboratory finding that is "over the limit" may make a prosecution appear inevitable. However, that result does not determine the outcome by itself. A drug driving prosecution depends on a series of forensic and procedural stages, including the roadside test, collection of the blood specimen, laboratory testing, and disclosure of the evidence to the defence. A failure at any stage can cause the prosecution's case to break down 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 cases come from the firm's own case history and illustrate the particular issue that caused each prosecution to fail.

1. The Blood Sample Was Too Small for Valid 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 for examination. The expert reached a clear conclusion: there was not enough blood in the specimen to conduct a valid analysis. The defence presented this finding to the Crown Prosecution Service together with a formal defence statement. Approximately one week before the scheduled trial, the prosecution discontinued the case.

Why this matters: strict requirements apply to the amount, handling, and division of blood specimens. Having a defendant's own portion independently analysed can identify defects that were not raised by the prosecution laboratory.

2. The Roadside Test Evidence Could Not Withstand Scrutiny 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" indicating cocaine. That description did not correspond with the way a positive result appears on the device, where a genuine positive produces two red lines. Elsewhere in the officer's evidence, there were also conflicting accounts of which drug had supposedly produced the positive result. Cross-examination at trial brought these inconsistencies to light. The prosecution ultimately accepted that it could no longer establish that the roadside test had been positive, undermining the legal basis on which the blood specimen had been requested. No further evidence was offered.

Why this matters: an officer's account of a roadside drug test is evidence and can therefore be challenged. Even apparently minor inconsistencies in the description or recording of the result may undermine the prosecution's case.

3. A Medical Explanation Was Not Properly Evaluated 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 had a needle phobia. When a person identifies a potential medical reason for being unable to provide a sample, the law requires a medical professional to assess whether that condition provides a reasonable excuse. No medical professional was brought in to conduct that assessment in Mr Franklin's case. An expert subsequently reviewed his medical records, consulted with him, and produced a report confirming that the phobia was genuine. In light of that evidence and the earlier procedural failure, the prosecution discontinued the proceedings before trial.

Why this matters: failing to provide a specimen does not automatically amount to an offence. Where there is a genuine medical explanation, it must be properly assessed by the police. A failure to obtain that assessment may significantly weaken the prosecution.

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

A number of the firm's cases involved the same important issue: the laboratory responsible for analysing the blood specimen had lost its UKAS accreditation for carrying out the particular tests required under section 5A of the Road Traffic Act 1988. In Mr T's proceedings, the problem was discovered only after the prosecution served its analytical data pack and the material was examined. Establishing that the laboratory had lost the relevant accreditation called the reliability of the analysis into question. On the trial date, the prosecution sought an adjournment, but the court declined the request. No evidence was then offered.

Why this matters: a laboratory result stating that a driver was "above the limit" depends on the reliability and proper accreditation of the laboratory responsible for producing it. If the laboratory did not hold the necessary accreditation for the test, the reported result may not withstand scrutiny in court.

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

Mr Singh's case presented an unusual situation because his blood specimen tested below the legal limit. Despite that finding, he was charged with the separate offence of driving while unfit through drugs. The prosecution relied in part on statements he had made during a police interview conducted months later. Professor Atholl Johnston was instructed as an expert and concluded that the concentration identified in Mr Singh's blood was inconsistent with the amount he had described taking and was unlikely to have affected him significantly. That expert evidence, together with a separate mistake in the hospital's paperwork, eventually resulted in the prosecution discontinuing the case.

Why this matters: the fact that a charge has been brought does not necessarily mean the underlying evidence supports it. A result below the legal limit, combined with expert analysis of what the detected concentration would realistically mean for a person's driving ability, can undermine a prosecution founded on less secure evidence.

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

After Mr Sharpe pleaded not guilty, the court established a timetable requiring the prosecution to provide its forensic report and the supporting material. The prosecution failed to meet that deadline. Further directions were issued at another hearing, but those requirements were also not complied with. When the proceedings reached a preliminary hearing only weeks before trial, the necessary disclosure remained outstanding. Rather than continue without its evidence properly in order, the prosecution discontinued the case.

Why this matters: the Criminal Procedure Rules impose substantive requirements on the prosecution concerning timely disclosure of evidence. Repeated failures to meet those obligations are not merely procedural details. Courts have repeatedly prevented the prosecution from relying on evidence served too late, and the consequences can be fatal to the case.

What These Cases Have in Common

These six proceedings did not end simply because the police "changed their mind." Each outcome arose from an identifiable and demonstrable problem with the prosecution: insufficient blood for testing, unreliable roadside-test evidence, a medical reason that was not properly assessed, a laboratory without the required accreditation, a test result that did not support the charge, or repeated failures to meet disclosure deadlines. In each instance, identifying the weakness depended on a defence team knowing which parts of the evidence and procedure required closer examination.

For anyone facing a drug driving allegation, the circumstances surrounding the traffic stop, the collection and testing of the specimen, and the evidence supporting the charge can be more significant than one figure appearing on a laboratory report. Consulting a specialist solicitor at an early stage provides an opportunity to determine whether similar evidential or procedural problems may be relevant to the individual case.

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