There are many policies which any company has to have in place with regards to their employees, and one which most business owners hope they never have to act upon is their drugs policy. Whether the action that might follow as result would be dismissal of an employee or paying for them to visit a drug rehab centre, knowing one of your members of staff is a drugs user, is never pleasant for any employer.
One of the values of a company or organisation having a clear and unambiguous drug policy is that everyone, from the owner or CEO, down through management and finally to all the employees, knows exactly what the procedures are going to be. These will cover drug testing, sanctions, and disciplinary consequences, should they apply. Bear in mind, not all companies will have immediate dismissal as the sanction, and they may instead go down the rehabilitation route.
The point here is that everyone should know what the policy is so that there can be no confusion and more to the point, no apparent unfairness should an employee be subject to disciplinary action due to them failing a drug test. This is as much an aid to the employer as it the employees as it gives them a clear understanding of what steps to take, rather than making it up as they go along.