Drug testing in the workplace


Drug-testing in the workplace can often be a difficult and daunting issue for employers and HR personnel to handle, where it is important to strike a balance between the individual rights of your employees with the health and safety of your workforce and the wider public.

Below we look at the rules relating to drug and alcohol testing at work, including whether testing can be refused by employees; the potential consequences of someone failing a test; and the importance of putting in place a drugs and alcohol policy.

What does the law say about drug-testing in the workplace?

As an employer you have a legal duty to ensure, so far as reasonably practicable, the health, safety and welfare at work of all your employees. Equally, you are under a duty to protect the health and safety of visitors to your premises, as well as anyone else who may be affected by the work undertaken by your employees.

Both these duties include managing any heath and safety risks posed by employees who may be under the influence of drink or drugs whilst at work, or during working hours, or otherwise unfit to work through drug or alcohol misuse.

As an employer, you can also be prosecuted if you knowingly allow an employee to be in the workplace while they are under the influence of alcohol or drugs, or allow drug-related activities to go on at work and you fail to act on this.

It is important to remember that even where substance misuse takes place outside of work, the effects can persist long after the point of consumption, seriously impacting an employee’s performance at work by impairing their judgment and concentration. This means that you must take appropriate measures, where necessary, to ensure that your staff are not a danger to either themselves or others whilst working as a consequence of alcohol or drug use.

Effectively managing the risks and effects of drugs and alcohol so that your staff do not pose any health and safety risk at work can be especially important where there are safety-critical elements to a job role, such as driving or operating heavy lifting equipment, or using machinery, electrical equipment or ladders. Here, the misuse of drugs or alcohol could have disastrous effects for the employee, co-workers, members of the public and the environment.

Otherwise, the need for drug-testing in the workplace will depend on the specific needs of your business and whether you feel able to justify a policy of random testing. Any approach to testing should be a risk-based one that takes into account the nature of the business, where relevant factors will include whether your organisation or roles within it are safety-critical, as well as concerns over reputation, alcohol or drug-related absenteeism or poor performance.

Before obtaining information through drug or alcohol testing, you must ensure that the benefits justify any adverse impact, unless of course the testing is required by law. As a matter of good practice, you should also only use drug or alcohol testing where it provides significantly better evidence of impairment than other less intrusive means.

When can an employer require a drugs or alcohol test?

Even in cases where there is clear and just cause for drug-testing in the workplace, there are still certain rules that must be followed. This includes obtaining the written consent of any individual to be drugs-tested, with separate written consent to be obtained for alcohol testing.

In some cases, consent may have already been obtained by way of a collective trade union agreement. Automatic testing for drugs and alcohol is especially common in industries where safety is essential to a person’s role, for example, in the transport or construction industry.

The need for drugs and alcohol testing can also be included in an employee’s contract of employment prior to them starting work for you, either by way of a specific contractual clause or under any incorporated workplace health and safety policy. This will then form the basis of advance consent for the employee to be subject to either periodic or random testing.

In the absence of any prior contractual agreement for drug-testing in the workplace, regardless of whether a person works in a safety critical area of your business and testing is required due to the nature of their work, you must still first obtain their written consent.

Can an employee refuse a drugs or alcohol test?

Drug and alcohol testing in the workplace is not enforceable by law, and an employee cannot be forced to provide a sample of urine, salvia, hair or blood. This means that an employee can refuse to be tested, although in circumstances where an individual is under a contractual obligation to agree to undergo screening and they refuse to do so, you may resort to taking disciplinary action against them, including dismissal, where appropriate.

Equally, if there is reasonable cause to believe an employee is under the influence of drugs and alcohol, or there is some other good reason for testing, for example, there has been an obvious decline in their performance at work or an increase in accidents, and they refuse to be tested, you may again consider taking action against them.

However, it is important to bear in mind that where an employee has not previously agreed to undergo random screening and they refuse to take a test, any unwarranted disciplinary action or attempts to force testing upon them, could result in that individual resigning and claiming constructive dismissal before an employment tribunal.

It is also important to remember that even though disciplinary sanctions and dismissal may be justified for any refusal to take a drugs and alcohol test, especially where a person is in a safety critical role, there may be other possible causes for any performance-related issues, such as stress, fatigue or physical illness that may need to be investigated.

What are the legal issues of drug-testing in the workplace?

Where drug-testing in the workplace is deemed proportionate to the risks to health and safety, or to the business involved, employers should still adhere to the following legal guidance:

  • Limiting testing to only those employees that need to be tested, where employees in different jobs will pose different health and safety risks, so the random testing of all workers will rarely be justified
  • Ensuring random testing is genuinely random, where it is unfair and deceptive to allow employees to believe that testing is random if, in fact, other criteria are being used
  • Not singling out an employee for testing unless this is justified by the nature of their job role, where it is potentially discriminatory to target an individual or group of employees
  • Using the least intrusive forms of testing practicable to deliver the benefits to the business that the testing is intended to bring
  • Informing employees what substances they are being tested for and the reasons why
  • Limiting testing to those substances and the extent of exposure that will meet the purpose(s) for which the testing is conducted
  • Basing any testing on reliable scientific evidence about the effect of particular substances on employees in those roles

Essentially, this means that employers who do decide to test workers to check their exposure to either drugs and/or alcohol should ensure that this is done lawfully and fairly.

It is also important to remember that collecting information by testing employees for drug or alcohol use is usually justifiable for health and safety reasons only. Where testing is otherwise used, for example, to enforce the rules and standards of your business, you must make sure these rules and standards have been clearly set out to workers in advance.

Before conducting drug-testing in the workplace, it is also crucial that you understand the processes and regulations involved. Any drugs and alcohol screening must be performed to a defined quality standard and in a legally secured and defensible way, ensuring samples cannot be contaminated or tampered with, and that testing procedures and analysis are accurate.

As such, it is always best to ensure that any testing is carried out by a laboratory accredited by the UK Accreditation Service and complies with the International Standard for laboratories.

If an employee fails a drug or alcohol test

If an employee agrees to to be tested for drugs or alcohol and they fail their test, depending on the circumstances involved, including the extent of any impairment on their ability to do their job and the risk posed to the health and safety of others at work, this may justify their instant dismissal. That said, a positive test result, in itself, does not necessarily mean that disciplinary sanction, or dismissal, can be justified, not unless there is clear evidence of illicit use at work.

Even where an employee’s conduct clearly points towards the use of drugs or alcohol at work, it is important that no disciplinary action is taken until the results have been confirmed – although the employee should not be allowed to continue to work if they are undertaking a safety critical role. In these circumstances, you may instead want to suspend the individual on full pay, pending receipt of their test results and any further investigation.

In some cases, you may also want to explore the underlying cause of any positive test result before considering dismissal. For example, employees with a medical condition which requires them to take a prescribed medication for which they have tested positive, may need to have reasonable adjustments made to their job role to minimise the impact of their medication. Any failure to support them in this way could amount to disability discrimination.

Further, your duty as an employer to ensure the health, safety and welfare of your employees also extends to their mental wellbeing, for example, where alcohol or drug misuse is a symptom of long-term stress. In these circumstances, even though you remain under a duty to protect the health and safety of others in the workplace, by treating the matter as a medical rather than a disciplinary issue, you may be able to retain an otherwise valuable employee.

This could be achieved by allowing that individual to take a reasonable period of time off work for recovery, encouraging them to seek specialist support, or even contributing to the cost of counselling or other treatment.

Drug and alcohol workplace policy

Given that consent is required for drug-testing in the workplace, if screening employees forms a necessary part of your health and safety risk assessment and risk management at work, it is important to have in place a drugs and alcohol policy that sets out the need for testing, how tests will be conducted, how this information will be used and the consequences for an employee of a positive test result or refusing a test altogether.

Your policy could be included within your overall health and safety policy, or as a separate document. Either way, this must be incorporated into the employee’s contract or staff handbook, forming part of their contractual terms and conditions of employment.

Your policy should also clearly explain the company rules relating to the use of drugs and alcohol at work, as well as the consequences of breaching these rules.

The use of drugs and alcohol has the effect of significantly impacting a person’s ability to perform their everyday duties, leading to reduced productivity, and posing a significant health and safety risk for themselves and others. By having in place a policy relating to drug and alcohol misuse, this can not only help to deter excessive or illicit use both inside and outside of work, but allow you to communicate to your workforce what support can be offered.

Drug testing in the workplace FAQs

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Legal disclaimer

The matters contained in this article are intended to be for general information purposes only. This article does not constitute legal advice, nor is it a complete or authoritative statement of the law, and should not be treated as such. Whilst every effort is made to ensure that the information is correct, no warranty, express or implied, is given as to its accuracy and no liability is accepted for any error or omission. Before acting on any of the information contained herein, expert legal advice should be sought.


Gill Laing is a qualified Legal Researcher & Analyst with niche specialisms in Law, Tax, Human Resources, Immigration & Employment Law.

Gill is a Multiple Business Owner and the Managing Director of Prof Services - a Marketing & Content Agency for the Professional Services Sector.

Legal disclaimer

The matters contained in this article are intended to be for general information purposes only. This article does not constitute legal advice, nor is it a complete or authoritative statement of the law, and should not be treated as such. Whilst every effort is made to ensure that the information is correct, no warranty, express or implied, is given as to its accuracy and no liability is accepted for any error or omission. Before acting on any of the information contained herein, expert legal advice should be sought.