Police have added a battery of tests to their armoury in a renewed crackdown on the city's drug-drivers.
From Thursday, officers will be able to compel drivers suspected of being under the influence of narcotics to give urine and blood samples if they fail a new five-part impairment test.
The changes follow 18 months of negotiations with lawmakers and come just weeks after the driver of a red-top minibus was arrested for drug-driving on suspicion of taking ketamine.
Superintendent Shylock Wong Yiu-ming said the tests were expected to be 95 per cent accurate and make it easier to determine whether motorists were under the influence of drugs.
They are based on models in Australia, Britain, the United States and Canada. A total of 200 traffic police officers have been trained to conduct them, with plans to expand that number to 1,200 officers. Wong said the officers empowered to run the tests were well qualified and would only apply them to drivers 'under reasonable suspicion'.
The police crackdown will focus on six illicit drugs: heroin, ketamine, Ice, cannabis, cocaine and Ecstasy.
A driver found to be driving under the influence of those drugs - even if his or her driving is not impaired - faces a maximum penalty of HK$25,000 and a three-year prison sentence. A driver's licence could also be disqualified for five years for a first offence and 10 years for a second.
Traffic police who suspect a driver of drug-driving will flag down the vehicle and conduct a breathalyser test to check for alcohol.
If drug use is suspected, the officer will check for pupil dilation and ask the driver to count backwards.
If the officer still suspects the driver has taken drugs, he or she will be taken back to a police station where one of the trained officers will conduct a 30-minute five-part impairment test.
The test assesses a person's alertness, the ability to process instructions and a sense of balance, co-ordination and depth perception.
It involves checking the driver's pupils, the ability to stand on one foot, count silently, count aloud, and to put a finger on his or her nose.
If the impairment test shows that drug use is likely, then the officer will take the driver to a hospital for a blood and urine sample. If it tests positive, the driver's licence will be suspended for 24 hours.
If the driver is unfit to complete the impairment test, then a blood and urine sample will be taken immediately but the driver's licence will not be suspended.
Drivers will face the same penalties if they take other drugs - illegal or prescribed - that render them incapable of controlling their vehicle.
The Road Safety Council has published a pamphlet to inform people of the effects various prescribed drugs might have on driving ability.
If a driver is found to be under the influence of drugs and alcohol at the same time, he or she can be prosecuted for breaking both drink - and drug-driving laws.
The number of arrests for drug-driving in Hong Kong last year, according to police. There were 84 arrests for drug-driving in 2010
The number of arrests for drink-driving in Hong Kong last year, according to police. There were 1,147 arrests for drink-driving in 2010