GoInspiration | Best Forex, Stock, Gadget, and Internet Information AppsPublished by Drug Driving Solicitors — specialist defence lawyers for drug driving charges across England and Wales.
Failing a roadside drug test is an unsettling experience, and for most drivers, what happens next is entirely unclear. The process that follows involves several distinct steps, each governed by specific legal rules and procedural requirements that can have a significant bearing on the outcome of any resulting case. Understanding those steps before they happen, or even while you are in the middle of them, puts you in a far stronger position.
This article walks through the seven key things that happen after a positive roadside drug test result, from the moment the device produces a reading to the day a case is heard in court. Each stage is explained in plain terms so that anyone facing this situation, regardless of their legal background, can understand what is happening and why it matters.
1. The Roadside Device Produces a Positive Reading
The process formally begins the moment a roadside drug screening device registers a positive result. These devices, which are type-approved by the Home Office for use by police in England and Wales, work by analysing a saliva sample taken from the driver using a swab. The most widely used device tests for cannabis and cocaine, though some forces use equipment capable of detecting a broader range of substances.
A positive reading on the device does not, by itself, constitute proof of a criminal offence. It is a preliminary indicator, not a definitive analytical result. The law distinguishes carefully between a screening test and an evidential test, and a roadside positive simply triggers the next stage of the process rather than establishing guilt.
That said, the consequences that follow from a positive reading are serious and move quickly. Officers are trained to respond to a positive device result by moving into a structured legal process, and from this point onwards, the situation becomes a formal police matter.
- The device must be type-approved for the drug detected
- A positive reading triggers the arrest and custody process
- The roadside result is not used as evidence in court proceedings
- The drug in question determines which device is required
2. The Officer Administers a Statutory Warning
Before the officer proceeds further, they are legally required to administer a statutory warning to the driver. This warning is a formal caution prescribed by the Road Traffic Act 1988, and it must be delivered in the correct form and at the correct point in the process. It informs the driver that they are being required to co-operate with the next stage and explains the consequences of failing to do so.
This step matters considerably more than most drivers realise. If the statutory warning is not administered correctly, whether it is delivered in the wrong form, at the wrong stage, or omitted altogether, it can render the subsequent requirement unlawful. That, in turn, can affect the admissibility of any evidence gathered as a result.
Defence solicitors will always examine the circumstances in which the warning was given as part of any case review. Officers are well-trained, but procedural errors do occur, and when they do, they can provide a viable basis for challenging the prosecution's case.
- The warning must be given before the evidential requirement is made
- Incorrect or absent warnings may undermine the lawfulness of the procedure
- Officers must follow the precise statutory wording
- This step is routinely reviewed by defence solicitors in all drug driving cases
3. You Are Arrested and Taken to a Custody Suite
Once the roadside screening test produces a positive result and the statutory warning has been administered, the officer will arrest the driver on suspicion of a drug driving offence under Section 5A of the Road Traffic Act 1988. The driver is then transported to the nearest custody suite, typically a police station, where the next stages of the process take place under controlled conditions.
Arrival at the custody suite is an important moment. The custody sergeant will book the driver in, explain their rights, and formally note the basis of the arrest. At this stage, the driver has the right to free and independent legal advice, which can be accessed by telephone or in person. Exercising this right is strongly advisable, regardless of the circumstances.
From the point of arrest, everything that happens is recorded and forms part of the case file. The custody environment can feel intimidating, but the process is structured and each step follows a defined sequence. Knowing what to expect makes it considerably easier to navigate.
- Arrest is made on suspicion of a Section 5A Road Traffic Act 1988 offence
- The custody sergeant explains rights, including the right to legal advice
- Free and independent legal advice is available at this stage
- Everything recorded in custody forms part of the formal case file
4. A Healthcare Professional Takes a Blood Sample
Once at the custody suite, the driver will be seen by a healthcare professional, usually a forensic physician or a qualified nurse, who is responsible for taking a blood sample. This is the evidential sample that will later be analysed by a laboratory, and it is the result of that analysis, not the roadside device reading, that forms the basis of any prosecution.
The blood-taking process follows a strict protocol. The healthcare professional must be satisfied that the procedure is medically appropriate, and the driver's consent is required. The sample is divided into two portions: one is retained for laboratory testing, and the other is offered to the driver to keep for independent analysis should they wish to instruct their own expert.
Accepting the offered portion of the blood sample is something defence solicitors routinely recommend. If the prosecution's laboratory analysis is later disputed, having an independent sample available gives the defence the ability to commission its own expert report. Declining the offered portion removes that option entirely.
- The evidential blood sample is taken by a qualified healthcare professional
- Consent is required for the procedure
- The sample is divided, with one portion offered to the driver
- Accepting and preserving your portion enables independent expert analysis
5. The Blood Sample Is Sent for Laboratory Analysis
After the blood sample has been taken and correctly packaged, the retained portion is sent to the police force's nominated forensic laboratory for analysis. The laboratory will test the sample for the specific controlled drugs and, where relevant, their metabolites, measuring the concentration of any substances detected against the legal limits prescribed in the Drug Driving (Specified Limits) (England and Wales) Regulations 2014.
The laboratory process is thorough and takes time. Depending on the workload of the nominated laboratory and the complexity of the sample, results can take anywhere from several weeks to several months to come back. This is one of the main reasons there is often a significant gap between the date of the alleged offence and any charging decision.
The legal limits are set at very low levels for illicit drugs, with zero-tolerance thresholds in practical terms, while prescription medications have separate, higher limits designed to allow therapeutic use. The concentration measured in the blood is the figure that will be presented as evidence if the case proceeds to prosecution.
- Results are measured against statutory specified limits, not general impairment
- Different limits apply to illicit drugs versus prescription medications
- Laboratory turnaround times vary and can be several months
- The laboratory report forms the central piece of prosecution evidence
6. You Are Charged or Told No Further Action Will Be Taken
Once the laboratory report has been received, the investigating officer and the Crown Prosecution Service review the evidence and make a charging decision. If the blood analysis confirms a controlled drug above the specified limit, the driver will typically be charged with an offence under Section 5A of the Road Traffic Act 1988. If the result does not support a charge, a no-further-action decision will be communicated to the driver.
A charge does not mean a conviction is inevitable. At this stage, a specialist solicitor will review the entire prosecution file, including the device type-approval records, the statutory warning administration, the blood sample chain of custody, the laboratory methodology, and whether the driver was lawfully stopped in the first place. Each of these areas can give rise to a legitimate defence.
Being charged is understandably stressful, but it is also the point at which legal representation becomes most critical. Understanding the full evidential picture before entering a plea is essential, and early specialist advice can make a material difference to how the case proceeds.
- The charging decision follows receipt of the laboratory report
- No-further-action decisions are also communicated at this stage
- A charge under Section 5A does not guarantee a conviction
- A full case review by a specialist solicitor should begin immediately on charge
7. Your Case Is Heard at the Magistrates' Court
Drug driving offences under Section 5A of the Road Traffic Act 1988 are summary offences, which means they are heard in the Magistrates' Court rather than the Crown Court. The driver will receive a court summons or, if released on bail, will be required to attend on the specified date. The case will be heard by either a District Judge or a bench of three lay magistrates.
If the driver pleads guilty, the magistrates will proceed to sentence, taking into account any mitigation and the circumstances of the offence. The mandatory minimum sentence for a first offence is a 12-month driving disqualification, though the actual ban imposed is frequently longer. A fine, a community order, or, in more serious cases, a custodial sentence may also be imposed.
If the driver pleads not guilty, a trial date will be set and the prosecution will be required to prove the case to the criminal standard. This is where thorough pre-trial case preparation by a specialist solicitor makes the most significant difference, as procedural deficiencies and evidential weaknesses that might otherwise go unchallenged can be identified and properly argued.
- Section 5A offences are summary offences heard in the Magistrates' Court
- The mandatory minimum disqualification for a first offence is 12 months
- Guilty pleas must be entered with full knowledge of mitigation available
- Not-guilty pleas require thorough pre-trial preparation by a specialist
Understanding What a Positive Drug Test Really Means for Your Future
A failed roadside drug test sets in motion a process with serious potential consequences, including a criminal conviction, a mandatory driving ban, financial penalties, and lasting effects on employment and insurance. But a positive roadside result is the beginning of a legal process, not the end of one. At every stage described above, there are procedural requirements that must be met, and a failure to meet them can have a direct impact on whether a prosecution succeeds.
The most effective thing any driver can do after failing a roadside drug test is to seek specialist legal advice as early as possible. The sooner a solicitor with specific expertise in drug driving cases is instructed, the more thoroughly the evidence can be reviewed and the more options remain open.
Frequently Asked Questions
What is a DG10 and how long does it stay on my licence?
DG10 is the DVLA offence code applied to convictions for driving or attempting to drive with a controlled drug above the specified limit, which is the standard Section 5A offence. Once recorded, it remains on your driving licence for 11 years from the date of conviction and is visible to any insurer querying the DVLA database. The practical effect on insurance premiums is almost always significant. A specialist solicitor can advise on the broader implications of a DG10 for your personal circumstances, including any effects on employment or international travel.
What happens if I refuse to provide a blood sample at the custody suite?
Refusing to give a specimen without a reasonable excuse is a standalone criminal offence under Section 7A of the Road Traffic Act 1988 and carries the same penalties as a drug driving conviction, including the mandatory 12-month disqualification. Reasonable excuses are defined very narrowly in law, and any medical reason put forward must be properly supported by evidence. It is essential to speak to a solicitor before deciding to refuse, as the legal threshold for a valid excuse is considerably higher than most people assume.
What are the most common grounds on which drug driving charges are successfully challenged?
The most frequently arising grounds include: failure to administer the statutory warning correctly prior to requiring the roadside swab; use of a screening device that was not type-approved for the particular drug detected; problems with the chain of custody of the blood sample; failure to offer the driver their portion of the divided sample; errors in the laboratory analysis process; and an unlawful stop and search. A specialist solicitor will systematically examine all of these issues as a matter of course, not merely the headline blood test concentration figure.
What if the drug detected in my blood was legitimately prescribed by my doctor?
A statutory medical defence is available under Section 5A(3) of the Road Traffic Act 1988 for drivers who are able to demonstrate that the drug was prescribed or supplied to them, that they took it in accordance with the medical advice given, and that their driving was not impaired. The defence is a genuine one, but it is considerably narrower in practice than many drivers initially assume. It requires proper evidencing and presentation to succeed. Drug Driving Solicitors has specific expertise in cases involving prescription medication, and early advice in these circumstances is particularly important.
Is it possible to drive while waiting for the laboratory results to come back?
Unless you have been charged and bail conditions specifically restrict your driving, or you are already disqualified for an unrelated reason, a pending investigation does not automatically prevent you from driving. However, it is worth reviewing your motor insurance policy carefully, as some policies contain clauses requiring disclosure of pending criminal investigations. If there is any doubt about your position, the safest course is to raise the question with your solicitor before continuing to drive.
How much time typically passes between failing a roadside test and being charged?
The process generally takes between two and six months, though it can extend beyond that in some cases. The principal cause of delay is the laboratory analysis of the blood sample, which depends on the turnaround times of the force's nominated laboratory and its current workload. Once the laboratory report is received, a charging decision tends to follow relatively swiftly. If six months have passed since the incident with no further contact, it is worth seeking specialist legal advice to understand where matters stand.
What should I do immediately after being released from custody following a drug driving arrest?
The most important step is to contact a specialist drug driving solicitor as soon as possible, ideally before leaving the custody suite if you have not already done so. You should preserve any documentation given to you at the station, note down everything you can recall about the roadside stop and custody procedure while it is still fresh, and, if you accepted your portion of the blood sample, ensure it is stored appropriately. Acting quickly gives a solicitor the best opportunity to review the full circumstances before any decision is made about how to respond to the investigation.
Drug Driving Solicitors is a dedicated law firm focusing exclusively on drug driving cases throughout England and Wales. If you have received a positive roadside drug test result and want a clear picture of where you stand, contact us to arrange a free initial consultation or visit drugdrivingsolicitors.co.uk. Taking early advice is at no cost to you, and it can prove decisive in determining how your case is resolved.