Supervisors and frontline managers are the eyes and ears of workplace safety. They are typically the first to notice when something is not right with a team member — and in the context of drug and alcohol impairment, that observation can be the difference between a safe shift and a serious incident.

Yet many organisations implement testing programs without adequately training the people who are most likely to encounter impairment firsthand. For-cause (or reasonable suspicion) testing is one of the most legally sensitive testing types, and getting it wrong can expose the organisation to unfair dismissal claims, discrimination complaints, and workers’ compensation disputes.

This guide covers what supervisors need to know to identify impairment, document their observations, and trigger for-cause testing correctly.

What Is For-Cause Testing?

For-cause testing — also referred to as reasonable suspicion testing — is conducted when a supervisor or manager has a reasonable belief that an employee is impaired by drugs or alcohol while at work. Unlike random testing, which is applied without individual suspicion, for-cause testing is directed at a specific person based on observable indicators.

Because it singles out an individual, for-cause testing carries higher legal scrutiny. The organisation must be able to demonstrate that the decision to test was based on objective, documented observations — not personal bias, rumour, or a hunch.

Observable Signs of Impairment

Supervisors should be trained to recognise the physical and behavioural indicators that may suggest impairment. These are observable facts, not diagnoses. It is not the supervisor’s role to determine whether someone has consumed a specific substance — only to identify that something appears wrong and that safety may be compromised.

Physical Indicators

• Bloodshot or glassy eyes
• Dilated or constricted pupils
• Slurred or unusually slow speech
• Unsteady gait or loss of coordination
• Tremors or shaking hands
• Unusual sweating or flushed skin
• Odour of alcohol or cannabis
• Drowsiness or difficulty staying awake

Behavioural Indicators

• Significant mood swings — sudden aggression, euphoria, or withdrawal
• Confusion or difficulty following instructions
• Unusually poor judgment or risk-taking
• Decreased reaction times
• Inability to perform routine tasks
• Unexplained absences or frequent bathroom breaks
• Erratic behaviour that is out of character

Important Caveats

Many of these indicators can also be caused by fatigue, medication, medical conditions, stress, or other non-substance-related factors. Supervisors should not jump to conclusions. The presence of one indicator alone may not be sufficient — it is typically a combination of indicators, or a marked change from the person’s normal behaviour, that warrants further action.

Training should emphasise that the supervisor’s role is to observe and document, not to diagnose. The test itself will determine whether substances are present.

Documentation Requirements

Thorough documentation is the foundation of a defensible for-cause testing decision. If the matter proceeds to a Fair Work Commission hearing or a workers’ compensation dispute, the organisation’s documentation will be scrutinised closely.

What to Document

• Date, time, and location of the observations
• Specific observable behaviours — Use factual language. “Employee was unsteady on feet and slurring words” is objective. “Employee appeared drunk” is a conclusion.
• Duration — How long the behaviours were observed
• Context — What was the employee doing at the time? Were they operating equipment, working at height, or performing safety-critical tasks?
• Witness details — Where possible, a second supervisor or manager should independently observe and document. Corroborating observations strengthen the case significantly.
• Employee response — Note what the employee said when approached, including any explanation offered

Many organisations use a standardised “Reasonable Suspicion Observation Form” that prompts the supervisor to record each element. This ensures consistency and reduces the risk of omissions.

How to Approach the Conversation

Approaching an employee suspected of impairment is one of the most difficult conversations a supervisor will have. It requires empathy, firmness, and a clear process.

Step-by-Step Approach

1. Remove the employee from safety-critical duties immediately. If you believe someone is impaired, do not wait for a test to be arranged before acting on the safety risk. Move them to a safe area.
2. Speak to the employee privately. Conduct the conversation away from other team members to preserve dignity and reduce embarrassment.
3. State your observations factually. “I have noticed that your speech appears slurred and you seem unsteady on your feet. I have a duty of care to make sure you are safe to continue working.”
4. Ask if there is an explanation. The employee may disclose a medical condition, medication, or other factor. Document whatever they say.
5. Explain the next steps. “Under our drug and alcohol policy, I am required to arrange for you to be tested. This is to ensure your safety and the safety of everyone on site.”
6. Arrange the test. Contact your testing provider or follow your internal testing procedure.
7. Arrange safe transport. The employee should not drive or return to safety-critical work until the situation is resolved.

What Not to Do

• Do not accuse the employee of being drunk or on drugs.
• Do not conduct the conversation in front of other employees.
• Do not allow the employee to continue working in a safety-sensitive role while awaiting the test.
• Do not delay — the longer you wait, the less reliable the test result and the weaker your documentation.

When to Escalate

Not every observation of unusual behaviour requires for-cause testing. Supervisors need guidance on when to escalate and when other responses may be more appropriate.

• Single, mild indicator — Monitor the employee. Document the observation. If the behaviour resolves, no further action may be needed, but the record should be retained.
• Multiple indicators or safety-critical role — Escalate to a senior manager or HR. Proceed with for-cause testing if the observations support a reasonable belief of impairment.
• Immediate safety risk — Remove the employee from duties immediately and escalate. Do not wait for a second opinion if you believe there is an imminent risk of harm.
• Employee discloses a substance use problem — Refer to your EAP and follow your policy’s support pathway. Testing may still be required, but the response should incorporate welfare considerations.

Legal Boundaries

Supervisors must understand the legal framework within which for-cause testing operates. Key principles include:

• Lawful and reasonable direction — A direction to submit to a drug or alcohol test is generally considered lawful and reasonable where it is supported by a clear policy, the policy has been communicated, and the request is based on documented, objective observations.
• Discrimination risk — For-cause testing must not be used to target individuals based on protected attributes such as race, age, disability, or union membership. The decision to test must be based solely on observed behaviour.
• Medical considerations — If an employee discloses that their symptoms are caused by a medical condition or prescribed medication, the organisation should seek further information before drawing conclusions. However, the employee may still be unfit for duty regardless of the cause.
• Refusal to test — Most policies treat a refusal to submit to testing as equivalent to a positive result. Supervisors should document the refusal and follow the policy’s escalation process.

Training Frequency and Format

Supervisor training on impairment identification and for-cause testing should not be a one-off exercise. Best practice includes:

• Initial training — All new supervisors and managers should complete impairment identification training as part of their induction.
• Annual refresher — A shorter refresher session each year to reinforce key concepts, update on any policy changes, and discuss any lessons learned from incidents.
• Scenario-based learning — Role-playing and case study exercises are far more effective than slide-based presentations. Supervisors need to practise the conversation, not just learn the theory.
• Record keeping — Maintain records of who has been trained and when. This is an important element of demonstrating due diligence.

Want to streamline your for-cause testing process with proper documentation and audit trails? Start a free trial of FairTest and give your supervisors the tools to manage impairment situations confidently and compliantly.