4.8 Drugs and Alcohol at Work: Legal Framework, Site Policy, Testing & Support

Why This Is a Site Management Issue

Every control described in this guide — the permit system, the hierarchy of control, the safe isolation procedure, the exclusion zone around a slewing excavator — assumes the person carrying it out is capable of judging risk and reacting normally. Alcohol and other drugs remove exactly that capability: reaction time, coordination, balance, depth perception and risk appetite are all affected, and the person affected is characteristically the last to notice. On a construction site the consequence is not poor productivity; it is a slinger misjudging a load, a scaffolder misjudging a gap, or a dumper driver misjudging a pedestrian.

CITB lists drugs and alcohol as a distinct learning outcome in Module 2 of the SMSTS syllabus, framed as the ability to identify, manage and support individuals affected by drugs and alcohol and understand the legal framework that regulates it. Note that the outcome contains three verbs — identify, manage and support — and that a purely punitive approach fails the third.

The Legal Framework

That last row is the nuance most site managers get wrong in both directions. Dependency itself is not automatically a protected disability, so a policy can treat it as a conduct matter. But dismissing someone without considering an underlying mental health condition or a prescribed-medication origin can expose the employer to a discrimination claim. Where the situation is not obvious, it goes to HR and occupational health, not to a site-level decision.

What a Workable Site Policy Contains

The construction phase plan should reference the drugs and alcohol policy, and the site induction must communicate it — a policy nobody has been told about will not survive a tribunal or an HSE investigation. A usable policy sets out:

• Scope. Who it applies to: direct employees, subcontractors, agency workers, delivery drivers, visitors. On a construction site the policy must bite on everyone who passes the turnstile, which means it has to be written into subcontract conditions, not just the employee handbook.
• The standard. What is prohibited — attending or remaining on site under the influence, consuming alcohol or drugs on site, and possessing or supplying controlled drugs on site — and whether the site operates a zero-tolerance or a threshold-based standard.
• Prescription and over-the-counter medicines. A duty to declare any medicine carrying a drowsiness warning or a caution against operating machinery. Codeine-based painkillers, sedating antihistamines, some antidepressants, muscle relaxants and strong analgesics after an injury all impair safety-critical performance while being entirely lawful. This is the most commonly overlooked route to impairment on a site, and the most easily managed: a temporary reassignment away from plant, height or driving for the duration of the course of treatment.
• Testing regimes and the circumstances that trigger them (see below).
• Consequences, including that unreasonable refusal to be tested is treated as a positive result under most policies — which is why the refusal consequence must be stated explicitly in advance.
• Support routes, including self-referral, occupational health, and any employee assistance programme.

Testing regimes

Testing only stands up if the process does: informed written consent, a competent and accredited testing provider, documented chain of custody for samples, a screening test confirmed by a laboratory confirmation test before any action is taken, and a medical review to check whether a positive result is explained by legitimate prescribed medication. A cheap unconfirmed screen used as the basis for a dismissal is both unfair and unreliable.

Identifying Impairment — and the Limits of Your Role

Indicators a supervisor or manager may reasonably observe include the smell of alcohol, slurred or rambling speech, unsteadiness or poor coordination, bloodshot or glazed eyes, pupils obviously dilated or constricted, mood swings or unusual aggression, uncharacteristic errors on familiar tasks, a pattern of Monday-morning or post-payday absence, and deteriorating timekeeping or appearance.

Two cautions matter. First, every one of those signs has innocent explanations — hypoglycaemia in an undiagnosed diabetic, a stroke, concussion from an unreported bump, extreme fatigue, a diabetic hypo, or a reaction to prescribed medication. Your job is not to diagnose. Second, acting on suspicion is nevertheless obligatory: the duty is to remove the risk, and you can do that without asserting a cause.

Immediate actions on reasonable suspicion

1. Remove the person from the work activity immediately and from any plant, height, live electrical work or vehicle. Do this calmly and privately where possible.
2. Do not leave them unattended, in case the cause is medical.
3. Involve a second manager as a witness, and follow the company procedure for invoking a for-cause test.
4. Arrange safe transport home. Never allow a suspected impaired worker to drive — doing so exposes them to prosecution under the Road Traffic Act 1988 and exposes the employer to liability for the consequences.
5. Record contemporaneously: what was observed, by whom, at what time, what was said and what was done. Recollections reconstructed weeks later do not survive scrutiny.
6. Escalate to HR and occupational health for the substantive decision. The site manager's job is the immediate safety decision, not the employment outcome.

Managing and Supporting the Individual

The distinction that drives the response is between misuse — a one-off or occasional lapse of judgement, ordinarily a conduct matter — and dependency, a health condition that a disciplinary process alone will not resolve. Construction has a well-documented culture problem here: a workforce with long hours, time away from home, physical pain from the job itself, and a strong stigma against admitting difficulty. That combination pushes dependency underground, which makes it more dangerous, not less.

A support-oriented policy therefore offers a route in: confidential self-referral before a test or an incident forces the issue, referral to occupational health, access to an employee assistance programme or specialist treatment services, reasonable time off for treatment, and a structured return-to-work with follow-up testing and a phased reintroduction to safety-critical tasks. Crucially, the policy should state that voluntary self-referral will be handled supportively, because a policy that punishes honesty guarantees concealment.

This connects directly to the mental health and wellbeing material in Section 4.6. Alcohol and drug misuse in construction is frequently a symptom of untreated stress, chronic pain or mental ill health rather than a standalone problem, and a site that manages the underlying causes well sees fewer of the consequences.