A drug and alcohol policy is essential to manage any employees who appear to be under the influence of these substances at work. Guidance on Alcohol and Drugs Policies are available from ACAS and the HSE. Policies should identify the company’s stance on drugs and alcohol in the workplace. Phrases such as ‘under the influence of’ drugs or alcohol are arbitrary without clearly clarifying the definition. Peritus Health Management recommends that it is defined as a ‘zero-tolerance’ to drugs and alcohol to avoid appeals on the grounds of what is a ‘safe’ level within the body. Each person is different and in the case of some drugs, the dose-response rate varies too much to be able to identify ‘safe’ levels. Policies should refer to the use of tests under varied circumstances – pre-employment, random or for cause – to determine whether an individual is ‘under the influence’ of drugs or alcohol and in breach of company policy. It should also explain how employees with identified problems will be managed.