Q: My company requires employees to submit to random drug tests. Will our drug testing policies “go up in smoke” as laws grow more lenient towards marijuana use?

A: That is a valid question considering that Pennsylvania became the 24th state to legalize the use of marijuana for medical purposes. In addition, several jurisdictions have legalized marijuana for recreational use. Importantly, however, marijuana use, distribution, and possession remains prohibited under federal law.

So what does this mean for employers?

As a practical matter, it means that, in some states at least (including Pennsylvania), employers may not discharge, refuse to hire or otherwise discriminate or retaliate against an employee regarding an employee’s compensation, and other terms and conditions of employment solely on the basis of the employee’s status as an individual who is certified to use medical marijuana. On the other hand, employers are not required to make any accommodation of the use of medical marijuana in the workplace, and may discipline or terminate an employee for being under the influence of medical marijuana in the workplace or for working while under the influence of medical marijuana when the employee’s conduct falls below the standard of care normally accepted for that position.

Where the picture gets hazier, however, is when an employee does not show any outward signs of impairment, but tests positive in a random drug test. This is quite possible, as marijuana stays in the human body for as long as 30 days.

Given that marijuana is considered a Schedule I substance prohibited by federal law, employers in most jurisdictions can maintain a “zero tolerance” policy mandating that applicants or employees who test positive for marijuana automatically will be terminated from employment. So far, at least, courts across the country have uniformly held that employers do not have to accommodate an employee’s use of marijuana, whether on or off duty.

But beware that in a small number of states, including Delaware, an employee may not be penalized for testing positive for marijuana where the employee has a valid prescription and there is no evidence that the employee used, possessed or was impaired by marijuana while at work.

The new Pennsylvania law does not speak directly as to whether an employer can rely upon a positive drug test as a reason for an adverse employment action in the absence of other evidence of impairment. While the law allows employers to discipline employees for being under the influence of medical marijuana in the workplace, it also limits such discipline when the employee works while under the influence of medical marijuana to when the employee’s conduct falls below the standard of care normally accepted for that position. Thus, the rule suggests that employers may not condition an adverse employment action on a positive drug test where the employee is a medical marijuana cardholder and the employee does not show outward evidence of impairment or his or her conduct does not fall below expected standards of care.

It remains to be seen how the Pennsylvania law will be interpreted. In the interim, in drafting a comprehensive drug testing policy, it is important for employers to consider the laws of every state in which it does business, and keep an eye on legal developments as this area of the law continues to evolve.