Employers often feel they’re between a rock and a hard place when it comes to drugs and alcohol in the workplace. On the one hand, they have a legal duty to accommodate employees who suffer the disability of addiction or who have been prescribed medication. On the other hand, they also have a legal duty to protect the health and safety of those employees, their co-workers and the general public.

It’s a pretty hot topic right now, not least because of the huge growth in medical marijuana prescriptions over the last couple of years. One estimate I saw, from the Canadian Life and Health Insurance Association, found the number of prescriptions had grown to more than 200,000 in 2016 from 8,000 in 2014. And, of course, there’s the fact that recreational marijuana is soon to become legal.

But the fact is that when it comes to employers balancing the duty to accommodate with their obligation to maintain a safe workplace, nothing has really changed. It all comes down to three things: creating a solid policy, informing and educating all staff and implementing the policy consistently.

Even if an employer has a policy around drugs and alcohol, it’s still important to look at it very carefully to make sure it covers all of the bases. In a lot of cases, that may mean updating and relaunching the policy, reaching out to educate staff and making sure all supervisors and managers are applying it consistently.

Read: Key questions for plan sponsors as marijuana legalization approaches

So what should be in a good policy? That’s really not all that complicated. (Just an aside here: policy is a responsibility an employer can’t hand off, but consultation and discussion with employee representatives or a joint health and safety committee can be useful in tailoring it to the workplace and smoothing the process of acceptance.)

There’s something close to consensus among human resources experts about the elements it should include:

A statement of commitment to the health, safety and well-being of all employees and the general public.

A prohibition on the use or possession of alcohol, marijuana or illegal drugs anywhere on the employer’s premises. (There may be a specific, well-defined exception for alcohol at certain company-sponsored and regulated social events.)

A prohibition on coming into the workplace while impaired by alcohol, marijuana or illegal drugs.

A requirement to report to supervisors the use of any prescription medications — such as marijuana and certain antihistamines — that potentially impair the patient’s ability to perform certain job tasks safely.

A statement of commitment to the employer’s duty to accommodate a disability and noting that accommodation and assistance are available to all employees.

And, finally, a clear statement on the progressive discipline, through warnings, official reprimands, suspensions and possible discharge, that applies to violations of the policy.

Read: CLHIA warns high prices for recreational marijuana will push users to medical system

Of course, every policy needs to have a set of procedures that spells out how it will work, who will do what and under which circumstances. An employer needs to spell that out just as carefully as the policy itself.

All employees — which include supervisors and managers, by the way — will report the use of any prescription medications the prescribing physician or pharmacist has informed them may cause impairment in the safe performance of some tasks.

Supervisors who become aware of possible indicators of impairment — such as performance lapses and the smell of alcohol — will remove the affected employee from performing potentially hazardous tasks and report the issue to the appropriate level of management.

Human resources or management will assess the situation and take appropriate action. That may include a return to work if the assessment finds no reason for further action; a warning, modified duties and referral to the employee assistance program for help; and possibly, depending on the severity, further steps in progressive discipline. All first incidents should include referral to the employee assistance program or other measures to assist in rehabilitation.

The employee may have to submit proof from a physician that the medications in question have been prescribed. Assessment by a medical practitioner may be necessary to assess the degree of impairment caused by medications and which accommodations may be in order.

Read: Employers concerned about ‘Wild West’ surrounding marijuana legalization: HRPA

When possible and practical, the employer will make accommodations to allow the employee to continue to work safely. At the same time, a key part of implementing a policy is to make sure all employees know and understand it. That’s where bulletin boards, newsletters, e-mail updates and department meetings come in. I would recommend doing all of those things. And as always with important issues, senior management needs to show a commitment. In the case of drug and alcohol policy, I suggest it should focus on the company’s commitment to employee well-being through accommodation on the one hand and protection on the other.

Finally, as with all policies, fair and consistent application is the key to long-term success. Supervisors need to be aware of their responsibility to monitor and intervene, which may require extra training.

I know from conversations that all of this is complex, sensitive and far from easy. But what I tell people is to deal with the issue step by step and keep the focus on the well-being of everyone in the workplace.

Bill Zolis is a senior employee benefits consultant at the Callery Group, in Whitby and Port Perry, Ont. This article originally appeared on Benefits Canada‘s companion website, smallbizadvisor.ca.