The legalization, decriminalization and permitted medical use of cannabis in many states has created some interesting challenges for the construction industry and worker safety. It seems nationwide legalization is inevitable. However, at present, marijuana is illegal under federal law.

Medical use of cannabis is permitted with a doctor’s prescription in 34 states and several U.S. territories. Recreational use of marijuana is legal in some shape or form in Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont, Washington, and Washington, D.C. These states heavily tax the sale of marijuana rather than make it an illegal substance.

There are a number of benefits stemming from the legalization of marijuana, which is why many states advocate for it. However, there are a number of adverse impacts as well. Marijuana use among workers can compromise safety.

Tetrahydrocannabinol (THC), the active ingredient in marijuana, can impair sensory perception, memory, motor coordination and judgment. As a result, employers should treat marijuana like any other drug, substance or alcohol. According to “How Legalized Cannabis is Affecting the Construction Industry,” published by Cotney Construction Law, Tampa, Fla.: “Employers can still drug test and make employment decisions based on an employee’s drug use, regardless of the legalization of prescribed medical marijuana. Implementing drug testing and a comprehensive drug policy can go a long way toward ensuring that your workers always maintain their physical and mental faculties.”

Construction work is physically demanding. Failure to perform could mean the loss of a job. Therefore, there is a high probability that construction workers will experience mental stress and physical pain. If they medicate with marijuana, this can put employers in a precarious position.

The construction industry is already riddled with job hazards, and any level of impairment caused by cannabis can lead to additional safety risks. These workers are around and operate heavy machinery, vehicles and other dangerous tools and equipment. The dangers are obvious for those working under the influence. Employers can be held liable if an accident occurs, even if it is the worker who is impaired.

Most states will not compensate a worker who was under the influence at the time of an accident, and no employer should be willing to expose their business to potential liability. This is true even if marijuana use is permitted in their state.

Workers are often drug tested as part of the hiring and pre-employment screening process. However, they are far less frequently tested on a recurring basis. Unfortunately, according to the Insurance and Risk Management Institute, Dallas, it is not uncommon for 25%–35% of pre-employment drug tests to come back positive.

What’s more shocking is that up to 5% of workers test positive for drugs even when they know in advance that they will be tested. Additionally, a recent study by the National Institute of Drug Abuse, Bethesda, Md., indicates employees who tested positive for marijuana had 55% more industrial accidents, 85% more injuries and 75% greater absenteeism compared to those who tested negative.

Additional challenges could arise in the event that a worker has been prescribed cannabis by a doctor. According to Matt Viator, senior legal associate for Levelset, New Orleans, “Employment laws can vary greatly from state to state, so depending on what state you’re in, it may be tough to enforce such a policy. However, because marijuana is still illegal on the federal level, the Americans with Disabilities Act will not be able to provide any federal protection.”

Most state health insurance programs do not pay for medical marijuana. Employers that decide to allow medical usage for an employee must ensure the safety of all other workers is not compromised. Employers may prohibit the use of cannabis for all employees and establish a zero-tolerance policy on it.

Because cannabis is illegal at the federal level, any and all use is prohibited. Keep in mind that federal statutes take precedence on federally funded projects. The law is very clear and strict when it comes to marijuana use, medical or not, for federal employees and projects. This includes all those employed by a federal entity, and all contractors, subcontractors and suppliers working on federal projects. That means no matter the circumstances or state laws, nobody involved with a federal project can use cannabis.

While OSHA has no regulations addressing cannabis use at this time, there likely will be in the future.