Police Methods Of Testing For Drug-Impaired Driving

Police methods for determining if people are cannabis-impaired while driving.

Canada's recent legalization of cannabis emphasizes a problem that police forces have been having for years: how do police test to determine if a person is driving while impaired by drugs? There is no generally accepted test that measures drug impairment as accurately as breathalyzer tests measure a person's level of alcohol impairment.

Currently, police determine if a driver is impaired by drugs by using Standard Field Sobriety Tests at the roadside if they suspect they are driving while drug-impaired. These are judgment tests. They will not suffice to meet the new standards for drug-impaired driving recently established by the federal government.

The New Federal Drug Impairment Criminal Offences

The federal government created three new criminal offences when it legalized cannabis use in the fall of 2018. The offences are based on the amount of Tetrahydrocannabinol (THC), the primary psychoactive ingredient in cannabis that impairs a user, in a driver's bloodstream. These offences are:

· A summary conviction offence for having more than 2 but less than 5 nanograms (ng) per millilitre (ml) of blood

· A hybrid offence for having 5 nanograms or more per millilitre of blood

· A hybrid offence of having a combination of 50 milligrams of alcohol per 100 millilitres of blood and 2.5 nanograms of THC per 1 millilitre of blood

Police can lay a charge under any of these offences if they can show that a driver's THC level fell within these limits within two hours of driving a vehicle after consuming cannabis. The problem for police is measuring the amount of THC in a suspect driver's blood.

Using Standard Field Sobriety Tests To Determine Driver Impairment

The Standard Field Sobriety Tests police administer at the roadside allow them to make a judgment call about the sobriety of a driver, but they do not measure the amount of THC. Police can ask a driver who fails the Tests to come to the police station for further evaluation.

A specially-trained evaluation officer will conduct a Drug Recognition Expert Evaluation (DREE). This ten-step process consists of:

· Additional sobriety testing

· Measuring clinical indicators such as blood pressure, pulse and body temperature

· Measuring pupil size in different lighting conditions

A driver who fails the DREE will be asked to provide a blood sample to measure the THC in their blood. The driver may refuse but will then face charges almost as grave as if they had failed the blood test.

New Roadside Saliva Testing

The federal government is trying to simplify this process by providing roadside saliva-testing devices to measure the amount of THC in a person's bloodstream. So far, it has approved one saliva testing device for police forces across Canada to use - the Drager DrugTest 5000. Few police forces use it. It has not performed well on tests in Canada. The Drager's problems are

· it does not work consistently in temperatures below 4 degrees Centigrade.

· it often returns 'false positives', suggesting a person is impaired when they are not.

The federal government is testing other devices while the Drager's manufacturer is upgrading it for Canadian use. Police will likely be using the Drager or a similar device in 2019. Again, drivers may refuse to give a saliva sample for testing but will be subject to criminal charges for refusing.

Legal Challenges

Initial uses of saliva-testing devices will be challenged under the Charter of Rights and Freedoms to determine if their use violates individual rights. Courts will determine if they will accept these devices' findings as evidence in a criminal trial.

If you give police a saliva or blood sample, consult an experienced criminal lawyer immediately. The police may have violated your Charter rights in one of three ways:

· either sample has been mishandled

· the blood sample has not been drawn properly by a qualified technician, or

· either sample was taken after the two-hour limit

An experienced criminal defence lawyer can determine if a rights violation has occurred and what can be done to protect your rights.