The UK government and Health and Safety Executive (HSE) state that there should be no need for widespread workplace drug testing. But with 31% of the UK population saying they have taken illegal drugs and 21% saying they continue to do so occasionally, there is increasing support for making drug testing a mandatory part of pre-employment screening.

Certain jobs might require testing if drug use could put company safety and security at risk. Employers have a duty under the Health and Safety at Work Act to ensure the health, safety and welfare of employees. If an employer knowingly allows an employee to continue working under the influence, and it poses a risk to others, they can be prosecuted. And should an employee cause an accident or death as a result of being under the influence of drugs or alcohol, the company may well be found liable.

Current industries where drug testing is common include the armed forces, public transport, police, prison service and the financial sector.

But drug testing in all sectors is on the rise, as employers are more conscious of the risk of litigation and malpractice. Reports suggest that the number of UK employers conducting workplace drug and alcohol testing, for new employees or randomly, have increased 470% since 2010.

Drug testing is currently legal in the UK but not enforceable by law. Workers must consent to testing prior to the test being carried out. Government guidelines recommend that employers should limit testing to only those employees that need it, ensure that tests are random, and not single out particular employees for testing unless justified by the nature of their jobs. Employers must also comply with data protection principles on handling sensitive personal data.

Pre-employment testing could affect the outcome of a hiring decision, and a candidate's refusal to consent to a drugs test can be a red flag and give reason not to hire someone.

Critics complain that companies are using drug testing as a way of controlling and monitoring staff. But with companies taking an increased interest in their employees mental and physical health to ensure a more productive, safe and healthy workforce, it is easy to see why many employers are deciding to routinely include drug testing as part of their pre-employment screening.