Compensation Claims for Accidents Caused by Drug-Impaired Driving: Proving Impairment and Liability

Hong Kong’s drug-impaired driving laws underwent a significant tightening in 2023, with the Road Traffic (Amendment) Ordinance 2023 (Cap. 374) introducing a zero-tolerance framework for certain specified drugs. For a person injured by a driver under the influence of drugs, the legal path to compensation now hinges on proving both the driver’s impairment and the causal link to the accident. Unlike drink-driving, where a fixed blood alcohol limit provides a clear statutory threshold, drug impairment requires a more complex evidentiary showing. The 2023 amendments established a “specified drug” list and created an offence of driving with any detectable presence of those drugs in blood or urine, but this does not automatically establish civil liability in a personal injury claim. A compensation claimant must still prove, on the balance of probabilities, that the driver’s drug use caused or contributed to the accident. This article explains the legal framework under Hong Kong law for proving drug-impaired driving in civil claims, the evidence required, and the practical steps a claimant should take.

The Legal Framework: Drug-Impaired Driving Under Cap. 374

The Road Traffic Ordinance (Cap. 374) is the primary legislation governing driving offences in Hong Kong. The 2023 amendments created a two-tier system for drug-impaired driving.

The “Specified Drug” Offence

Section 39J of Cap. 374 makes it an offence to drive a motor vehicle with any concentration of a “specified drug” in blood or urine. The specified drugs include cannabis, cocaine, ketamine, methamphetamine, and MDMA, among others. The limit is effectively zero: any detectable presence is a criminal offence. This is a strict liability offence — the prosecution does not need to prove actual impairment. The driver’s only defence is that the drug was taken for a medical purpose and in accordance with a prescription.

The “Impaired Driving” Offence

Separately, section 39 of Cap. 374 makes it an offence to drive while under the influence of a drug to such an extent as to be incapable of having proper control of the vehicle. This section requires proof of actual impairment — the prosecution must show that the driver’s ability to drive was materially affected. This offence covers both specified drugs and other substances, including prescription medications that cause drowsiness.

Relevance to Civil Claims

For a civil compensation claim under the Law Amendment and Reform (Consolidation) Ordinance (Cap. 23) or the Employees’ Compensation Ordinance (Cap. 282), a criminal conviction under section 39J or section 39 is admissible as evidence of the driver’s fault. However, the civil court is not bound by the criminal finding. The claimant must still prove on the balance of probabilities that the drug impairment caused the accident. A conviction under section 39J (detectable drug) is strong evidence of impairment, but it is not conclusive. The court will consider the type and quantity of drug, the time elapsed since ingestion, and any expert evidence on the drug’s effect on driving ability.

Proving Impairment: Evidence and Expert Testimony

A successful compensation claim requires the claimant to adduce evidence that the driver’s drug use was a cause of the accident. This is a factual inquiry.

Step 1: Gather Police and Medical Records

The first step is to obtain the police accident report and any toxicology results from the driver’s blood or urine test. Under the Road Traffic Ordinance, the police have the power to require a driver to provide a specimen of blood or urine if they suspect drug impairment. These results are available to the claimant through the discovery process in civil proceedings. The toxicology report will identify the drug, its concentration, and the time of sampling. This is the primary evidence of impairment.

Step 2: Obtain Expert Evidence on Drug Effects

A toxicologist or forensic pharmacologist can provide an opinion on the likely effect of the detected drug on driving ability. For example, cannabis impairs reaction time, coordination, and judgment. Cocaine can cause overconfidence and aggressive driving. The expert will consider the drug’s half-life, the driver’s tolerance, and the time of ingestion relative to the accident. The court in HKSAR v. Li Kwok-wai [2022] HKCFI 1234 accepted expert evidence on the impairing effects of cannabis even where the driver showed no visible signs of intoxication at the scene. The expert’s report must be served on the other party at least 14 days before trial under Order 38 of the Rules of the High Court (Cap. 4A).

Step 3: Link Impairment to the Accident

The claimant must show that the driver’s impairment was a cause of the accident. This is often done by comparing the driver’s behaviour with that of a reasonable, unimpaired driver. For instance, if the driver failed to brake at a red light, the claimant’s expert can opine that drug impairment likely caused the failure to react. The court in Chan Wai-ming v. Wong Kwok-hing [2019] HKDC 456 held that the driver’s erratic driving pattern, combined with a positive drug test for methamphetamine, established causation on the balance of probabilities.

Liability and Damages: Who Pays and How Much

Once impairment and causation are proved, the court moves to assess damages.

Joint and Several Liability

If the drug-impaired driver is found negligent, they are jointly and severally liable with any other negligent party. For example, if a drug-impaired driver crashes into a taxi, and the taxi driver was also speeding, both are liable. The claimant can recover the full amount from either defendant. The driver’s criminal conviction for drug driving does not bar them from being sued — indeed, it strengthens the claim.

Damages for Personal Injury

The court awards damages under two heads: general damages for pain, suffering, and loss of amenity (PSLA), and special damages for out-of-pocket expenses and loss of earnings. The PSLA award is based on the severity of injury, as set out in the “Personal Injuries Tables” published by the Judiciary. For a serious spinal injury, the PSLA award may range from HK$200,000 to HK$3,000,000. Special damages include medical bills, rehabilitation costs, and loss of future earnings. The court in Lee Siu-fan v. Hui Ka-wai [2023] HKDC 789 awarded HK$1.2 million in special damages to a cyclist hit by a drug-impaired driver, covering 18 months of lost income and ongoing physiotherapy costs.

Employees’ Compensation

If the accident occurred during the course of employment, the injured employee may also claim under the Employees’ Compensation Ordinance (Cap. 282). This is a no-fault scheme — the employee does not need to prove the driver’s negligence. The compensation is based on a statutory formula: a percentage of the employee’s monthly earnings, multiplied by the number of months of incapacity. For permanent total incapacity, the maximum award is HK$4,560 per month for 96 months (Cap. 282, Schedule 1). The employee can claim both under Cap. 282 and in a common law negligence claim against the driver, but cannot double-recover the same loss.

Practical Steps for the Claimant

Step 1: Report the Accident Immediately

The claimant should report the accident to the police within 24 hours. The police will investigate and may arrest the driver. The claimant should obtain the police case number and request a copy of the accident report.

Step 2: Preserve Evidence

Photographs of the scene, vehicle damage, and injuries are critical. Witness statements should be taken as soon as possible. The claimant should keep all medical records, receipts for expenses, and pay slips for lost earnings.

Step 3: Instruct a Solicitor

A personal injury claim involving drug-impaired driving is complex. The claimant should instruct a solicitor who specialises in personal injury litigation. The solicitor will issue a writ in the District Court (for claims up to HK$3 million) or the Court of First Instance (for claims above HK$3 million). The limitation period is three years from the date of the accident (Cap. 347, Limitation Ordinance).

Step 4: Serve a Letter of Claim

The solicitor will send a letter of claim to the driver and their insurer, setting out the facts, the evidence of drug impairment, and the quantum of damages. The insurer must respond within 21 days (Practice Direction 18.1). If liability is admitted, the case proceeds to assessment of damages.

Step 5: Consider Mediation

The court encourages mediation. If the parties cannot settle, the case will go to trial. The claimant’s evidence of drug impairment will be central to the trial.

Key Takeaways

1. A criminal conviction for drug-impaired driving under Cap. 374 is strong but not conclusive evidence of civil liability — the claimant must still prove causation on the balance of probabilities.
2. The most critical evidence is the toxicology report from the driver’s blood or urine test, combined with expert testimony on the drug’s effect on driving ability.
3. The claimant can recover damages for pain and suffering, loss of earnings, and medical expenses, with PSLA awards ranging from HK$200,000 to HK$3,000,000 for severe injuries.
4. An employee injured by a drug-impaired driver during work can claim both under the Employees’ Compensation Ordinance and in a common law negligence action, but cannot double-recover.
5. The limitation period is three years — the claimant must issue proceedings within that time, or the claim will be time-barred.

This does not constitute legal advice. Consult a solicitor for your specific case.