Substance Use and the Safety Line: A Decision Tree

Why this matters

Someone who is impaired on a jobsite is a danger to themselves, the crew, the customer, and anyone on the road in a company truck. This is not about judging a person's life or their off-hours. It is about one line: an impaired person does not work today. Getting that call wrong can cost a life. Getting it right costs an awkward conversation. Take the awkward conversation every time.

Start here: is the person safe to work right now?

You are not diagnosing addiction and you are not running a lab. You are answering one question: can this person operate tools, drive, and make decisions safely in the next several hours? If you have a reasonable, good-faith belief the answer is no, the person comes off the work for the day. Full stop. You sort out the why afterward.

The conservative call is the default. When you are unsure, you treat it as unsafe and stand the person down. A wrong "stand down" wastes a shift. A wrong "go ahead" can kill someone.

If you see clear signs of impairment

Slurred speech, smell of alcohol or cannabis, unsteady balance, bloodshot eyes, pupils that do not track, confusion, or behavior that is off from how the person normally is.

• Pull the person aside, in private, away from the customer and the rest of the crew.
• State what you observed plainly: "You seem off and I am not comfortable with you running tools or driving today." Describe behavior, not accusations about their character.
• Take the keys. Do not let an impaired person drive a company vehicle or their own. Arrange a ride.
• Get them home safely, then deal with policy and follow-up when they are sober.

Document what you saw and what you did, the same day, in plain factual language. You are recording observations, not a verdict.

If the signs are subtle or you are just not sure

Maybe they are quiet, slow, smell faintly of something, or made a careless mistake. You do not have a slam-dunk case, but something is wrong.

• Trust the instinct enough to slow down. Reassign them to low-risk tasks well away from blades, heights, live circuits, and the wheel while you assess.
• Ask a direct, non-cornered question: "You seem off your game today, everything alright?" Fatigue, illness, a new medication, or a rough night at home can mimic impairment. The fix differs, but the immediate step (off the dangerous work) is the same.
• If after that you still cannot get comfortable, you stand them down for the day. Unsure equals unsafe.

If it is prescription or over-the-counter medication

Legal does not mean safe to operate equipment. Plenty of common medications carry "do not operate heavy machinery" warnings.

• The person does not have to tell you what they take or why. Medical privacy is real.
• They do have to be fit for the duty. If a medication makes someone drowsy or slow, that person is on light duty or off the dangerous work until it clears, same as anyone.
• This is a fit-for-duty conversation, not an interrogation about their health.

If it is a recurring pattern, not a one-off

A single bad day is handled in the moment. A pattern is a different problem and it is above a crew lead's pay grade to solve alone.

• Keep handling each unsafe day the same conservative way: off the work, get them home safe.
• Loop in the owner or manager. A pattern needs a real conversation about the job, and often about help. Many shops point people to an employee assistance resource or a treatment path rather than just firing.
• Lead with safety and the person's worth, not punishment. People come back from this when the door is left open.

The lines that never bend

• An impaired person never drives. Take the keys, arrange the ride.
• An impaired person never runs tools, climbs, or touches live systems.
• When you are unsure, you treat it as unsafe.
• You handle it in private and you handle it with respect.

You will feel like the bad guy for an hour. The alternative is a phone call to a family. There is no contest.

References

• OSHA guidance on workplace impairment and fitness for duty
• Trade-standard fit-for-duty and substance policies
• Employee assistance program (EAP) resources, where the shop offers one
• See related: The Weather Stop-vs-Go Decision Tree; Reporting an Injury: Do It Now