This article is the first installment in a three-part series adapted from our December 15, 2015 Legal Lunch with Laura webinar presentation: “Workplace Drug Testing in the Era of Legal Marijuana—Guidance for Employers.”

Over the last decade or so, conventional attitudes about marijuana have begun to change. Starting with the legalization of marijuana for medical purposes, several states—such as Colorado, Washington, and Oregon—have recently passed legislation licensing the full-blown sale of cannabis for recreational use. National polls frequently indicate that people in most, if not all, states support similar measures. These trends signal a meaningful shift in our country’s attitudes and policy toward psychoactive drugs. Soon, marijuana may be as prevalent as alcohol or tobacco.

Of course, that does not mean employers must or should condone marijuana use in the workplace. Countless companies have contacted us about this issue, usually asking some form of the following question:

“Many of my employees go out for a smoke break during the day—
What if, during that break, employees are smoking marijuana?
What do I do? What are my rights as an employer?”

This uncertainty is not surprising. There are myriad national and state laws that tend to confuse employers about what rights they have to maintain a safe workplace and sober workforce.

Overview Of Existing Marijuana Legislation

Almost half of the states in the U.S. now have some form of legislation sanctioning marijuana use or possession:

  • Many states have decriminalized marijuana possession in small amounts.
  • 23 states, the District of Columbia and Guam now authorize and control marijuana use through comprehensive public medical programs.
  • 17 states allow individuals to use marijuana certain low-THC, high-cannabinoid formulations for “medical reasons in limited situations or as a legal defense.”
  • Colorado, Washington, Oregon, and Alaska have all recently legalized recreational marijuana, which individuals ages 21 or older can buy in limited quantities at dispensaries or approved retail locations.

These laws appear to clash with federal statute, which still classifies marijuana a Schedule I substance under the Controlled Substances Act. The government considers Schedule I substances dangerous drugs “with no currently accepted medical use and a high potential for abuse.” Distributing a Schedule I drug such as marijuana is a federal offense, although federal enforcement remains inconsistent and will likely continue to abate with evolutions in popular sentiment and pressure from assorted interest groups.

One upshot of federal prohibition is that, regardless of your state’s laws, you can lawfully terminate or take disciplinary action against employees who are under the influence of marijuana while on the job.  Let’s take a look at some of the drug’s detrimental effects, along with the various times drug testing can benefit your workplace.

The Negative Effects Of Marijuana

Why should employers care whether their employees are under the influence? According to Colorado’s Retail Marijuana Public Health Advisory Committee, which monitors the substance’s health effects, “the drug poses a serious threat to workplace safety and productivity.” As the committee concluded, “the legal status of marijuana does not remove this threat.” Here are a few more statistics that indicate how impaired employees put themselves and their coworkers at risk:

  • A cannabis user’s decreased ability to filter and process information can last long after consuming the substance. One study demonstrated that 7 out of 9 aircraft pilots exhibited signs of impairment 24 hours after smoking a marijuana cigarette.
  • Employees who test positive for marijuana cause 55% more industrial accidents, experience 85% more injuries, and have absenteeism rates 75% higher than those who test negative.
  • Driving after smoking marijuana doubles an individual’s car crash risk.
  • Research has found substantial evidence linking an individual’s marijuana use to memory impairments for at least seven days after that individual’s last use.

When To Drug Test

We recommend employers administer drug tests during five stages in an employee’s or candidate’s career:


Before offering a candidate a job, or even conducting an interview, you may want to subject the individual to a drug test for the five illegal drug panels. A drug test that includes prescription drugs, in addition to the five illegal drug panels, can be administered only after a conditional job offer. Pre-employment screening deters drug users from applying for positions, thus saving you time and narrowing the pool of applicants. It can also function as another point of assessment and communicates your workplace’s standard of acceptable behavior to each candidate prior to employment.


It is almost never a bad idea to test an employee who has recently caused an accident that may have been precipitated by substance abuse. Perhaps this person was in an auto accident, injured himself or a co-worker, or damaged a piece of machinery. Your handbook should outline the circumstances that would require a post-incident drug test (e.g., property damage in excess of a certain amount of money, injuries that required hospitalization or medical attention, an accident that required the intervention of police). Drug testing in this situation may provide a defense against a workers’ compensation claim.


Maybe the individual has exhibited observable, uncharacteristic behaviors such as slurred words, a blank stare, glassy eyes, an unstable walk, unusually high or low energy levels, or general incomprehensibility.   A drug test based on reasonable suspicion, promotes workplace safety, and may provide cause to terminate or deny benefits to an employee.


A company may want to consider a drug test upon return to duty after  an employee has suffered an accident, undergone surgery, participated in an alcohol recovery or drug rehabilitation treatment program, or missed work for an extended period of time for any reason.. Doing so helps reduce your risk of a drug-impaired workforce and, for employees with substance abuse problems, regularly occurring drug tests can effectively deter relapse.


In contrast with testing for reasonable suspicion, random drug tests are not meant to target specific individuals. Instead, employers should use an objective method like random number generation to justify the subjects they test. Random testing sends a powerful message to the workforce that you will not tolerate drugs and is a powerful tool for discovering drug users, with a positivity rate several times higher than periodic testing. (For further testing data, be sure to download the PDF version of this presentation.)