Imagine recreational cannabis use is legal.  What happens when, in a workplace drug test, an employee tests positive for cannabis but claims he/she should be allowed to work because they are not impaired? Is it for the employee to prove they are not impaired, or for the employer to prove they are impaired and does it matter?

Standard workplace drug tests measure whether or not there are specific drugs in the person’s system and the level of those drugs. They do not measure impairment. Under the Health and Safety at Work Act 2015 the employer has a duty to provide and maintain a work environment that is without risk to health and safety of workers and other persons in the workplace. Integral to this is the obligation to eliminate risks where practicable. Risk levels and risk assessments surrounding drug use will vary from workplace to workplace. It would be a high risk strategy for an employer to base decisions about whether a worker testing positive for cannabis can continue working (even though legal) based on a perceived level of impairment or otherwise, particularly in high risk industries such as manufacturing, construction, transport and forestry. Sending the worker home, suspension until clean, and/or dismissal will be legally justifiable if reasonable in the circumstances and a substantial reason for the action taken is to comply with obligations under the Health and Safety at Work Act 2015.


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