Drug Driving

The offence of driving, attempting to drive, or being in charge of a vehicle while the level of a specified controlled drug in the body exceeds the legal threshold came into force on 2 March 2015. This is a strict liability offence, which means the prosecution does not need to prove impairment if the relevant drug is present above the prescribed limit. The legislation covers a list of specified substances, including both illegal drugs and certain medications that may be lawfully prescribed.

This offence was introduced to deal with cases where a driver had taken drugs but there was not enough evidence to prove they were impaired under section 4 RTA 1988 (driving whilst unfit through drugs).

The main offences that commonly arise in drug driving cases are:

• driving, attempting to drive, or being in charge of a motor vehicle while over the specified limit for a controlled drug under Section 5A of the Road Traffic Act 1988
  
• driving whilst unfit through drugs under section 4 RTA 1988
  

A conviction for drug driving is serious and can lead to a mandatory driving disqualification of at least 12 months. A second relevant offence within 10 years can lead to a ban of at least 36 months. Depending on the facts of the case, sentencing can range from a fine to a community order, and in more serious cases up to 6 months’ imprisonment.

An allegation of driving whilst unfit through drugs under section 4 RTA 1988 can attract similar penalties.

The offence under Section 5A is committed where the concentration of a specified drug in the blood is above the legal limit. The prescribed levels for illegal drugs are set on a near zero-tolerance basis, although they are intended to avoid criminalising mere accidental exposure. The law can apply not only to unlawful substances but also to certain prescribed or over-the-counter medications, depending on the drug and the level found.

Ultimately, responsibility rests with the driver to ensure they are fit and lawful to drive. Although medical professionals may warn patients about side effects or driving restrictions connected to prescribed medication, the legal responsibility remains with the person behind the wheel.

Specified Drug Limits

Illegal drugs – blood concentration limits

• Benzoylecgonine (main cocaine metabolite) – 50µg/L
• Cocaine – 10µg/L
• Delta-9-Tetrahydrocannabinol (Cannabis) – 2µg/L
• Ketamine – 20µg/L
• Lysergic Acid Diethylamide (LSD) – 1µg/L
• Methylamphetamine – 10µg/L
• Methylenedioxymethamphetamine (MDMA / Ecstasy) – 10µg/L
• 6-Monoacetylmorphine (Heroin) – 5µg/L
  

Certain medicinal drugs – blood concentration limits

• Amphetamine (for example Dexamphetamine or Selegiline) – 250µg/L
• Clonazepam – 50µg/L
• Diazepam – 550µg/L
• Flunitrazepam – 300µg/L
• Lorazepam – 100µg/L
• Methadone – 500µg/L
• Morphine – 80µg/L
• Oxazepam – 300µg/L
• Temazepam – 1,000µg/L
  

Roadside Drug Testing

Police will often request a roadside drug test in much the same way they may require a preliminary breath test for alcohol. However, an officer can only require a preliminary drugs test in certain circumstances. This may include where they suspect a person has a drug in their body or is under the influence of drugs, where a moving traffic offence is suspected, or where the driver has been involved in a collision.

The roadside drug screening device is usually a saliva test. It works by analysing a small sample taken from the mouth. Results are typically shown by indicator lines on the device, and the test generally screens for cannabis and cocaine. If the roadside result is positive, the driver will usually be arrested and taken to a police station for a blood sample, which is then relied upon in any later prosecution. Refusing to cooperate with the roadside procedure may itself lead to arrest.

Investigation for Driving Whilst Unfit

Even where a roadside drug test is used, the police may still investigate the separate offence of driving whilst unfit through drugs under section 4 RTA 1988. This is particularly relevant where the later blood result comes back below the prescribed limit, but there is still evidence suggesting the driver was impaired.

In these circumstances, officers may carry out a Field Impairment Test. This can involve physical coordination checks such as walking in a straight line, standing on one leg, touching the nose, and other observations including pupil size, balance, speech and general coordination. If the officer remains concerned, the driver may be taken to a police station for further procedure and a blood sample.

Blood Samples and Failure to Provide

Although the legislation refers to blood or urine, the specimen taken in these cases is typically blood. As with alcohol investigations, refusing to provide a specimen without a lawful excuse may amount to a separate offence. In some situations, a genuine medical reason for refusing or being unable to provide blood may amount to a reasonable excuse.

If no blood sample is obtained, the police may still continue investigating a section 4 RTA 1988 allegation, because proving impairment does not depend on showing that a drug level exceeded a specific threshold.

Where the laboratory result shows that the concentration exceeds the statutory limit, the usual charge will be under section 5A RTA 1988. If the result falls below the legal threshold, the police may instead pursue the alternative allegation of driving whilst unfit under section 4 RTA 1988.

In practice, both evidential routes should be properly considered by investigators, although this does not always happen.

Why a Drug Driving Conviction Matters

A conviction for a drug driving offence can have serious long-term consequences. In addition to a driving ban and sentence imposed by the court, drivers may also face increased insurance premiums, difficulties with employment, and restrictions when travelling abroad. In some cases, entry into countries such as the United States may become more difficult following a conviction.

Statutory Defences

There are two statutory defences available to a charge under section 5A RTA 1988.

The first applies where the drug had been prescribed or lawfully supplied for medical or dental purposes, the driver took it in accordance with the directions given by the prescriber or supplier, and possession of the drug immediately before taking it was lawful.

This defence places an evidential burden on the defendant. In practical terms, the accused must produce enough evidence to raise the issue. Once that has been done, the prosecution must prove beyond reasonable doubt that the defence does not apply.

The second statutory defence is available only in “being in charge” cases under section 5A(1)(b). It mirrors the position in alcohol cases. The defence is that, at the relevant time, there was no realistic likelihood of the defendant driving while over the legal limit.

It is important to note that these statutory defences do not prevent the police or prosecution from also pursuing an allegation under section 4 RTA 1988 where impairment is said to exist.

Laboratory Procedure and Timing

Once a blood sample has been taken, usually at a police station or occasionally at hospital, it is normally divided into two parts. One sample is retained for police testing and the other may be made available to the suspect if requested. A leaflet is usually provided explaining what can be done with that sample, although in practice opportunities for independent testing can be limited.

The police sample is then sent to an accredited laboratory. As with alcohol cases, strict handling, storage and transport procedures matter. This is especially important because some drugs, including cannabinoids, can break down relatively quickly. The timing of the blood draw is also significant, since the prosecution will want the result to reflect the level at the time of the alleged driving. In many cases, a sample is taken within around an hour of arrest, but delays can occur depending on the availability of a doctor or healthcare professional.

After release from custody, or discharge from hospital if relevant, the driver will usually wait for the laboratory result. As a general guide, results often take around 4 to 8 weeks. If the result is above the prescribed limit, a charge under section 5A RTA 1988 is likely. If not, the police may continue to consider an impairment-based offence under section 4 RTA 1988.

Why Specialist Legal Advice Matters

Drug driving law is highly technical and often turns on procedure, forensic evidence and the way the police handled the case from the outset. If you have been accused of drug driving, it is important to obtain specialist legal advice as early as possible.

A careful review of the evidence may reveal possible lines of defence or challenge, including:

• the reliability and continuity of the blood sample
• the way the blood was taken and whether correct medical procedure was followed
• whether the required warning about failing to provide a sample was properly given under s.7(7) Road Traffic Act 1988
• whether the driver gave informed consent to the taking of the sample
• whether the roadside drug test and arrest were lawful
• whether the prosecution can prove that the defendant was actually driving or attempting to drive
• whether a medical condition or other genuine reason explains a refusal or failure to provide a sample
• whether drugs were taken after driving, meaning the level at the time of driving may have been different