Clarity amidst the (purple) haze: How is the Fair Work Commission dealing with Cannabis-related dismissals?

Seeing the forest for the weed 

Employers have duties to ensure the health and safety in their workplaces by, as far as possible, eliminating or minimising risks. One obvious risk to be eliminated is ensuring workers are not intoxicated or impaired by drugs while performing their role. In many workplaces, this involves adopting a drug and alcohol policy which may empower an employer to take disciplinary action in response to a breach of the policy. This is particularly important in safety-critical industries such as construction, mining and transport.

The consumption of medicinal cannabis has become more widespread with data from the Therapeutic Goods Administration (TGA) showing more than 1 million prescriptions have been issued since medical legalisation in Australian occurred in November 2016. In 2022– 2023, 11.5% of people in Australia had used cannabis in the previous 12 months, equating to around 2.5 million people. As with many drugs, the presence of cannabis does not disappear from the body immediately. This presents employers with a difficult scenario to manage, which is coming before the Fair Work Commission for consideration with increasing frequency.

We have reviewed two of the Commission’s recent decisions, in an effort to help provide some clarity amidst the haze.

Wight v Queensland Rail 

The Fair Work Commission decision of Zachary Wight v Queensland Rail Limited [2025] FWC 1758, handed down 20 June 2025 by Commissioner Spencer, provides useful insights into unfair dismissal cases involving cannabis consumption by an employee. The decision also hints at some of the complex legal and psycho-social issues that can exist between dual recreational and the medical purpose consumption of cannabis and the impact this can have in cases involving the termination of employment.

The applicant, Mr Zachary Wight, a long-serving shunter with Queensland Rail (QR), filed an unfair dismissal application after his employment was terminated when he tested positive for Delta-9-tetrahydrocannabinol (THC) cannabis presence in bodily fluids. This occurred on his first day back at work following extended medical leave.

The work of a shunter is an inherently dangerous role in a safety critical work environment involving train movements and overhead electrified equipment. The applicant was self-represented in the proceedings, during which he admitted to self-medicating and not disclosing cannabis consumption to manage the exacerbation of a psychiatric injury allegedly stemming from the QR workplace.

By way of background, THC is an intoxicating medicinal compound found in the cannabis plant. THC is highly lipophilic, meaning it readily dissolves in fats and oils but not in water. This characteristic significantly impacts how THC is absorbed, distributed, metabolised, and eliminated by the body depending on its method of ingestion (inhaled, oil, capsule, pastille etc). The duration of intoxicating effects by inhalation can vary by person, but generally only lasts a few hours, but potentially up to five hours when ingested in higher doses.

Mr Wight admitted to inhaling “three or four lungsful” of THC three days before resuming work duties with QR, but argued that the consumption occurred while on leave and was linked to a psychiatric condition that he alleged to stem from mistreatment by QR. He argued that THC can typically be detected in saliva for up to 24-72 hours after consumption, and he should thus be excused.

The Commission was told that QR has a documented zero-tolerance drug policy for safety-critical roles and the applicant had been previously, explicitly informed by QR’s Chief Medical Officer (CMO) that he could not consume, or be affected by, THC-containing cannabis while completing rail safety work. Mr Wight was given periods of personal leave, leave without pay and periods of light administrative duties under a Health Improvement Plan prior to returning to work in his role, following previous self-reports of thoughts of self-harm in the train yard environment. Those reports took on additional significance given a previous QR employee had attempted self-harm by touching overhead wires. Mr Wight was given notice that a ‘return to work’ test under the policy would occur upon resuming duties.

Standards Australia and Standards New Zealand set standards and guidelines regarding the collection of samples for oral fluid (saliva specimen) drug tests. AS/NZS 4760:2019 updated and lowered the amount of THC that needs to be present for a test to show a positive result. THC screening tests reduced from 25 ng/mL to 15 ng/mL and confirmatory tests from 10 ng/mL to 5ng/mL.

QR appears to follow these updated rules, using 5 ng/mL as the limit for detecting THC on-site.

QR did not appear to test for intoxication or impairment, just presence; for completeness, testing for impairment is difficult, and there is no accepted standard for doing so and it differs from person to person. So, when Mr Wight’s reading came in at 17ng/mL, being above the level permitted by QR’s policies, it provided grounds for QR to begin the process of investigating, and ultimately terminating, his employment for breach of policies, procedures and code of conduct.

The Commission found there was a valid reason for Mr Wight’s termination, being the attempt to return to work in a safety-critical role with elevated levels of THC in the saliva breached QR’s Alcohol and Other Drugs Policy and Code of Conduct. The Commissioner particularly considered the high-risk rail yard environment of the role. While the Commission accepted Mr Wight had a psychiatric injury (supported by a Workers’ Compensation “Review Decision”), it concluded the employer’s actions in managing his health and work environment were reasonable. The Commission emphasised that self-medicating with cannabis did not excuse a breach of the applicant’s safety obligations to his employer.

Mr Wight had also been given notice of the reasons for dismissal, the opportunity to respond, and access to a support person during key disciplinary steps. The employer’s reliance on expert medical opinion (including from its CMO) was noted and Mr Wight’s claim that the cannabis may have remained in his system longer than expected was not accepted or excusive of the breach, particularly given the high concentration level detected. In those circumstances, the dismissal of Mr Wight was found not to be harsh, unjust or unreasonable.

Parks v WorkPac

More recently, the Commission in Maxwell Parks v WorkPac Pty Ltd [2025] FWC 2316 found a different employer to have unfairly dismissed an employee who had returned multiple non-negative results for THC in his system, despite having a comprehensive Alcohol and Other Drugs policy.

Maxwell Parks had been employed by labour hire employer WorkPac Pty Ltd since May 2021, who placed him on assignment to perform work at the Boundary Hill Mine in Central Queensland, operated by Batchfire Resources Pty Ltd (Batchfire). Mr Parks’ role required him to operate dozers and massive rear dump trucks with loads over two hundred tonnes. Mr Parks was dismissed on 4 February 2025 after returning non-negative drug tests for THC in body fluids on consecutive shifts. Mr Parks contended that the dismissal was harsh, unjust and unreasonable, citing confusion over policies, alleged procedural flaws in the drug testing process, and his belief that he was fit for work.

Mr Parks’ employment was governed by WorkPac’s policies, his employment contract and Batchfire’s site fitness-for-duty policies. Both sets of documents included obligations around being “fit for work” and complying with drug and alcohol testing. However, the policies contained inconsistencies: Batchfire’s procedures allowed return to work after a negative retest, while WorkPac maintained a stricter “zero tolerance” requirement. Parks argued this confusion meant he was not adequately on notice of which standard applied.

On 25 January 2025, Mr Parks consumed cannabis. The next morning, before work, he used a self-test kit which Batchfire made available to workers on its site, which returned a negative result (i.e. no cannabis detected). He proceeded to work, swiped on, and was later directed to undergo a drug test because his housemate had tested ‘non-negative’. Mr Parks’ first test was non-negative, but an immediate retest was negative. Despite the Batchfire policy suggesting he could resume work, he was sent home pending a B sample laboratory confirmation.

When Mr Parks returned for his shift the next day, he again self-tested before work, which again returned a negative (i.e. no cannabis recorded) result. On site, his first test was recorded as negative, signed off by a supervisor, and he was allowed to commence duties. Later that shift, however, he was recalled and told the test had “turned” non-negative; importantly, this occurred more than 10 minutes after the test was taken, which was outside the manufacturer’s stated validity window. A retest using an already opened kit also returned non-negative. Parks requested another retest, which was initially denied, then belatedly allowed but overtaken by arrangements for a confirmatory B sample. He ultimately failed that further test, with cannabis remaining detectable in his system.

WorkPac issued Mr Parks with a show cause letter on 31 January 2025, citing alleged breaches of the Fitness for Work Policy and Code of Conduct. Mr Parks responded, admitting he had consumed cannabis but insisted he had relied in good faith on self-testing kits and did not believe he was impaired. Despite this, WorkPac determined that two consecutive non-negative results substantiated serious misconduct and terminated his employment effective immediately on 4 February 2025.

Mr Parks argued before the Commission that Batchfire’s testing procedures were flawed and not followed consistently: sealed kits were not used, test results were altered after being signed off, and results were read outside validity times. He maintained that the conflicting cut-off thresholds created unfairness (the oral fluid self-testing kits provided by Batchfire were aligned to the AS 4760:2006 standard cut-offs (25 ng/mL), while WorkPac workplace testing was aligned to AS/NZS 4760:2019 (which has a lower threshold of 15ng/mL) for screening of THC. He also relied on case law questioning the connection between positive tests and actual impairment. He further explained his cannabis consumption was linked to situational mental health distress.

WorkPac as respondent submitted that Mr Parks was bound to comply with its policies, which took precedence over Batchfire’s. They emphasised their “zero tolerance” approach to drugs in the workplace and argued that confirmatory laboratory tests showing THC in Parks’ system on consecutive days demonstrated breaches of policy. Given his role operating heavy machinery, WorkPac considered dismissal proportionate and necessary to maintain workplace safety.

The Commission accepted there was a valid reason for dismissal due to positive THC results and the inherent safety risks of Mr Parks’ role. However, it found the termination harsh because WorkPac failed to adequately consider the conflicting policies, the self-testing regime that had fostered Mr Parks’ belief that he was fit for work (which the Commission found to be a genuinely held belief), and the procedural inconsistencies in the testing process. The Commission ruled the dismissal unfair, declined reinstatement due to loss of trust and safety concerns, and awarded Parks $37,222.50 in compensation as the appropriate remedy (being six months’ compensation, halved to account for the employee’s misconduct).

What lessons do these two decisions hold for employers?

These decisions show how similar underlying facts can produce materially different outcomes. Both employers had a valid reason to dismiss, but only Workpac’s dismissal was found to be unfair, with substantial compensation ordered.

In reviewing both decisions, the following themes emerge:

1. Be cautious of relying on results from drug testing devices as the sole basis for disciplinary action as false negatives and false positives do happen.

2. Enforcement of ‘zero-tolerance’ approaches in, for example, high-risk mining, construction, transport and logistics roles, can be upheld but must be well documented and consistent. A failed drug test may not, on its own, be a sufficient basis to end someone’s employment.

3. Employers are best placed to defend any claim if they provide employees procedural fairness through the testing and show cause process.

4. The Commission will balance safety and rights: while it is perfectly legitimate for safety critical industries to have strict standards, employees retain rights under the Fair Work Act 2009 (Cth) and the Commission will not excuse unfair process even where drug consumption is admitted.

Conclusion

Novel therapeutics (not just cannabinoids) is an evolving area impacting employment related law. Recently, the Allan Government in Victoria has committed to ‘progressing’ reforms recommended by a state inquiry into workplace drug testing, passing a motion through Victoria’s Upper House of Parliament. Advocates are positioning for changes to be made to the Occupational Health and Safety Act 2004 (Vic) to regulate workplace drug testing and amendments to the Equal Opportunity Act 2010 (Vic) to prevent discrimination against individuals due to a medical condition or taking a prescribed medication, such as medicinal cannabis that contains THC.

The TGA at the Commonwealth level is also conducting a public consultation to gather information from stakeholders on their knowledge, experiences and observations of the use of unapproved medicinal cannabis products in Australia. This has been prompted by increasing public and professional concern about the safety risks associated with unapproved medicinal cannabis products, particularly those containing higher levels of THC, noting there are large numbers of Australians accessing and using these products.

A challenge in law reform is that, globally, there is no independent, accepted and validated means to verify intoxication from THC containing cannabis. Therefore, using arbitrary cut-off limits from presence detection only in saliva (or urine or blood), testing devices using Australian Standards as a proxy for intoxication may have significant, inherent evidentiary limits in future cases. Unlike alcohol intoxication, THC impairment is not linear by volume consumed and every person metabolises it differently.

It’s important to be on the front foot on this subject matter but also to stop, pause and reflect before taking employment law related actions that may be detrimental to your organisation or staff.

When you do need to take action, it's critical to have robust supportive medical evidence, fully consider any anti-discrimination and unfair dismissal risks, and seek legal advice if in doubt about your position.