The significant rise in workplace drug testing in the UK could see a dramatic rise in companies overstepping the mark and acting in an unlawful manner– says a leading employment lawyer.

The warning follows a report on the BBC’s website in which four leading screening companies say that workplace drug testing has increased significantly in the UK. The four companies, which are Alere, Synergy Health, LGC Group and BioClinics, claim big rises, with one firm stating that the number has increased by up to 470% over the last four years.

Under the current laws, workers cannot be made to take a drugs test, but if they refuse when the employer has good grounds for testing, they may face disciplinary action. These regulations are usually in the contract or staff handbook.

Many businesses are looking to clampdown on drug use, including the use of so-called ‘legal highs’, but if an employer oversteps the mark, they could face claims from employees including unfair dismissal (where they treat the presence of drugs as a misconduct issue), breakdown in working relationships or potential discrimination.

Lianne Gray, LGC Group’s strategic account manager for occupational drug testing, said employees in safety-critical roles – such as operating heavy machinery or driving – and government agencies were most likely to be screened.

But she said there is a growing trend for drug testing to be conducted in “more normalised industries”, including retail and health companies, as businesses look to “safeguard not only the business, but also the reputation in the field they work in”.

“Traditionally we see requests for amphetamines, cocaine, cannabis, opiates,” she said. “Now we’re seeing more requests for things like ketamine, steroids, and also for novel psychoactive substances – or legal highs as they’re otherwise known.”

Glenn Hayes, an employment Partner at national law firm Irwin Mitchell, said: “Drug and alcohol testing was traditionally limited to safety critical roles, but we have also seen this become a more wide spread issue with random and routine testing being implemented across a wider range of sectors and roles.

“Whilst it can be lawful and appropriate to do so, there must be a clear strategy for why the testing is required and, even then, the testing must be no more intrusive that is absolutely necessary to meet its purpose.

“A clear policy is recommended so that the extent and implications of testing are understood by employees and training given to those reviewing tests so that any action following the tests is appropriate and fair. The key difficulty with testing for the wider range of drugs, such as steroids, is that it may infringe personal privacy. If it does not impact on their conduct or performance at work, businesses must be extremely careful.”