25 Jan 2024
Is there a test for impairment due to drug use?
At a recent Employment Relations Authority hearing, expert witnesses were called to address the issue of whether the employee could be considered “under the influence” of cannabis following a specific test result. This was for the purpose of interpreting the wording in the Collective Agreement during a disciplinary process. There was first a discussion about “under the influence” and “impairment” which are words that are commonly used in employment policies. Here are some key points from the expert witnesses that employers may find helpful:
- We agree a one off LCMSMS result of 97ng/mL for THC-COOH (urine) cannot indicate the time, the dosage, the frequency or the potency of the previous use(s) of cannabis.
- We agree a one off LCMSMS result of 97ng/mL for THC-COOH (urine) cannot confirm impairment due to cannabis at the time of donation.
- We all agree that a one off LCMSMS result of 97ng/mL THC metabolites (urine) could have arisen from cannabis usage 36 hours prior, but also agree that the same result could have arisen from usage 2 hours prior to donation (i.e. earlier on the morning of the test).
- Due to the above point we all agree that the one off LCMSMS result of 97ng/mL (for THC metabolites in urine) cannot exclude impairment from cannabis at the time of donation, nor can it pinpoint as to the timing or the frequency or potency of ingestion in this particular case.
- We all agree that none of us would get into a plane/car/train knowing that the driver/pilot/operator had just donated a urine sample of 97ng/mL…
- We all agree that none of us would get into a plane/car/train knowing that the driver/pilot/operator had just donated a urine sample that was non-negative (i.e. before it had gone to the lab).
- We all agree that both the above situations are due to potential safety concerns of the operator.
- We all agree that there is no international standard for impairment in an Occupational setting that is validated across safety critical industries (i.e. not road users).
Many Drug and Alcohol policies refer to “under the influence of” or “impairment”. One of the expert witnesses stated that it is widely accepted in safety critical/sensitive industries and workplaces that the aim of a drug testing program and policy is to reduce the potential for impairment from drugs and alcohol, and only a negative result can confidently exclude impairment.
You may like to review the wording of your policy to clarify that a non-negative drug test is considered potential serious misconduct. If you adjust the wording in your policy, you need to consult with employees and consider their feedback before finalising your new policy, and you need to be able to demonstrate that all employees are aware of the new policy.
Give our People & Culture team a call if you need assistance in this area: 0800 383 737.
Meredith MacKenzie | People & Culture Specialist
