Since 1996, when California became the first state to legalize marijuana for medical purposes, 29 states and Washington, D.C., have followed suit, with eight states and the District of Columbia also legalizing recreational use of the drug.

Due to these changing laws on marijuana usage in various states across the country, employers in the HVAC construction and sheet metal industry find themselves under a cloud of uncertainty regarding how these changes in law might affect them and what — if any — policy changes they need to make to stay on the right side of the law. For example, sheet metal contractors may wonder whether an employee with a prescription for medical marijuana must be allowed to take his or her “medicine” before heading into work, or even use it while working on the jobsite, without undermining the employer’s legal duty to provide a safe working environment for all employees.

Contractors are also likely questioning how these changes in law affect their ability to enact and enforce company policies and protocols regarding employee drug use, drug testing and workplace safety.

Further complicating matters is the fact that under federal law, marijuana is still illegal. Under the U.S. Constitution’s supremacy clause, federal law supersedes all states laws that conflict with it. As a result, possessing, growing, distributing or prescribing marijuana is still a federal criminal offense everywhere in the U.S., regardless of state laws that may legalize it. Under the Obama administration, the Justice Department was lenient with its enforcement of these federal laws in states where marijuana had been legalized. Although the Trump administration so far appears to be maintaining this position, a change in the government’s policy regarding federal drug enforcement is always possible, and with it the entire legal marijuana industry could come crashing down.

Editor’s note: On Jan. 4, the White House announced it was planning to rescind the Obama-era directive that discouraged federal prosecution of most marijuana crimes in states that had legalized the drug for medical or recreational uses. Its effect on local laws is not clear.

So while many may celebrate the expanding legalization of marijuana and the exponential growth of the marijuana industry, the reality is complicated for employers and can have a huge impact on the way an employer runs its business. This article explores a few of the biggest pitfalls and concerns facing employers in the construction industry on the issue and discusses things contractors should consider when determining how to manage and minimize the risk marijuana usage may pose to their businesses. 

ADA accommodations

The Americans with Disabilities Act was enacted in 1990 to provide individuals who have recognized disabilities the same access to employment opportunities and benefits available to people without disabilities. Under the ADA, employers with 15 or more workers are prohibited from discriminating against qualified individuals and must provide accommodations, within reason, to qualified applicants or employees with a disability that will allow them to participate in the application process or to perform the essential functions of the job.

the devil's lettuce

One of the biggest concerns presented by medical marijuana legalization is whether under the ADA, employers are required to provide a reasonable accommodation for medical marijuana users. For example, by permitting the employee to use marijuana while working or while on break to help alleviate a disability or medical condition. For now, the answer is clear: No.

Many state statutes expressly state that employers are not required to accommodate medical marijuana use, possession, or impairment while at the workplace. In other states where the statutes are silent on the issue, courts have uniformly held that employers have no obligation under the ADA to accommodate medical marijuana usage because the act expressly states that a person using illegal drugs is not a “qualified individual with a disability” and since marijuana is still illegal under federal law, it is considered an illegal drug under the ADA. However, even though employers are not required to provide an accommodation for marijuana usage in the workplace, employers may still be obligated under the ADA to provide other reasonable accommodations for the employee’s underlying disability or condition.

Employers should always keep in mind their duty to engage in an interactive process with their employees to determine if a reasonable accommodation other than medical marijuana use can be provided.

Discrimination concerns

Another related concern is whether employers can be subject to disparate treatment discrimination claims under the ADA for disciplining, refusing to hire, or terminating an employee because of his or her medical marijuana use or status as a medical marijuana cardholder. Again, because medical marijuana use does not qualify for protection under the ADA, any discrimination claims brought under the ADA on this basis should fail, as long as the adverse action was the result of the employee’s medical marijuana usage and not because of the employee’s underlying disability. 

However, employers are not entirely in the clear on this issue: In a handful of states where medical marijuana has been legalized, including Arizona, Connecticut, Delaware, Illinois, Maine, Minnesota, Pennsylvania and Rhode Island, employers are prohibited from discriminating against individuals based solely upon the person’s status as a medical marijuana cardholder. Employers under federal contracts are exempt from this provision.

Drug testing and zero tolerance

Many, if not most, employers in construction incorporate some form of drug testing into their hiring and firing practices and procedures. Many states offer discounts on employers’ workers’ compensation insurance premiums if the employer establishes and maintains a drug-free workplace, which usually includes a drug-testing component. Some companies choose to go a step further by enforcing zero-tolerance policies, in which employees who fail a single drug test are fired, regardless of whether the prohibited substance was legally obtained or whether it was used only while off the clock or outside the workplace. With the increasing legalization of marijuana at the state level, many employers are left wondering whether they can continue to maintain and enforce their drug-testing and zero-tolerance policies or whether they must start making exceptions for marijuana users. 

Because marijuana remains illegal under federal law, employers still have the right to test for it, even in states that have legalized it for medicinal or recreational use. In general, if companies want to continue receiving discounts on their worker’s compensation premiums, they will need to continue enforcing their drug-free workplace policies, including the drug-testing components.

For some federal contractors, the U.S. Drug-Free Workplace Act may require or allow those companies to enforce zero-tolerance drug policies across the board, even for medical marijuana usage. Similarly, the Department of Transportation prohibits marijuana use for workers in safety-sensitive jobs in the industries it regulates. As a result, such policies almost certainly would be enforceable by employers in those industries. 

Lack of clarity

For other employers in the construction industry, the waters become much murkier on the issue of zero-tolerance policies as applied to medical marijuana users. Unlike tests for alcohol and most other illegal drugs, tests for marijuana do not always indicate that the employee is currently impaired or under the influence at the time of testing. Since marijuana can stay in an individual’s body for weeks, an employee’s off-duty use of medical marijuana could cause him or her to fail a subsequent workplace drug test. Because of this, several states, either by statute or court ruling, require employers to prove evidence of impairment in addition to a positive drug test. This can be quite a daunting task as there is little guidance concerning what constitutes impairment from marijuana use. 

So what should employers do? Contractors in states where medical marijuana is legal need to check their state’s laws to determine if their state is a “plus impairment” state. In these states, a failed drug test is not enough by itself to warrant firing a worker. Instead, employers must also prove that the employee was impaired or under the influence of the drug while at work. 

Weed and the Law

If they are not in a state with such a law, employers can continue to maintain and enforce their existing zero-tolerance policies. However, if their state does have the plus-impairment requirement, employers should consider revising their policies as they pertain to medical marijuana usage, either by exempting medical marijuana users altogether or by adding in an “impairment investigation” component and providing comprehensive training to supervisors on how to detect and document signs of impairment. Even if not required by law, employers may still want to consider making such changes if they find that they are losing too many good employees under existing policies due to off-duty, legal medical marijuana usage.

Safety concerns

In 2015, out of 4,379 worker fatalities in private industry, 21.4 percent — roughly one out of every five — was in the construction industry.  Adding marijuana usage into the mix of such an inherently dangerous profession raises serious concerns about both employee and third-party safety. The Occupational Safety and Health Administration Act does not contain a specific provision that prohibits drug use or impairment on a job site. However, as many contractors are familiar, OSHA does impose a general duty requiring employers to maintain and provide a place of employment “free from recognized hazards that are causing or are likely to cause death or serious physical harm.”   

So what is a “recognized hazard”? Employees performing ductwork fabrication while impaired? Employees operating a press brake or other heavy machinery after smoking a joint? What about an administrative assistant working a desk job while under the influence? Although there are no sure answers as to what OSHA would consider a recognized hazard involving medical marijuana usage, OSHA rarely entertains excuses from employers. Therefore, any leniency in enforcing a workplace safety program in order to accommodate medical marijuana users may result in an OSHA citation for a safety violation.

Marijuana usage undoubtedly raises safety concerns for employers in the HVAC construction industry. These concerns are are best addressed before any related accidents or injuries occur. Employers should review and update their workplace safety, drug use and testing policies as necessary, and should remind employees that on-the-job impairment is not tolerated under any circumstances, including for medical marijuana.

Model policies

Employers who choose to maintain zero-tolerance drug policies should clearly communicate to employees that any marijuana use, including legal, off-duty medicinal usage, may subject them to discipline up to and including termination. Employers that are considering revising their policies to permit off-duty legal medicinal marijuana usage should carefully consider all relevant safety laws, the risks of a workplace accident, the duties performed by each individual employee and other safety concerns before deciding whether to permit off-the-clock medical marijuana usage by some or all of its employees.   

If workers are in safety-sensitive jobs for which marijuana use is completely prohibited under federal or state law, such an exception obviously should not be made. For other employees whose duties might be significantly impacted by drug use and create safety issues for themselves, other employees, or third parties, then employers would be wise to seek further advice from a medical professional concerning whether the employee can safely perform his or her job duties while taking medical marijuana.

Whatever policy decisions HVAC construction employers make, they should provide comprehensive employee education on those policies and procedures and the impact of legal changes. They should train their managers and supervisors on how to spot potential policy violations and how to handle issues that may need further consideration. They should also offer employee assistance where appropriate, such as for disabilities under the ADA or serious health conditions under the Family and Medical Leave Act. Additionally, employers should review their policies, ideally at least once a year, to ensure they are addressing and complying with the latest legal requirements. It is every employer’s responsibility to know the laws governing the operation of his or her business. With the construction industry already heavily regulated, it’s important now more than ever to make certain your company is in full compliance. 

Medical pot OK in 30 states

These states have legalized marijuana possession and use for approved medical conditions. It remains banned under federal law.


  • Alaska
  • Arizona
  • Arkansas
  • California
  • Colorado
  • Connecticut
  • Delaware
  • Florida
  • Hawaii
  • Illinois
  • Louisiana
  • Maine
  • Maryland
  • Massachusetts
  • Michigan
  • Minnesota
  • Montana
  • Nevada
  • New Jersey
  • New Mexico
  • New York
  • North Dakota
  • Ohio
  • Oregon
  • Pennsylvania
  • Rhode Island
  • Vermont
  • Washington
  • West Virginia
  • Medical marijuana is also permitted in Washington, D.C., and the U.S. territories of Puerto Rico and Guam.

Fully legal marijuana less common

In addition to medical use, to date seven states and Washington, D.C., have legalized recreational use of marijuana for adults over 21. Regulations may restrict sales and possession. Public consumption is banned.


  • Alaska
  • California
  • Colorado
  • Massachusetts
  • Nevada
  • Oregon
  • Washington

Voters in Maine approved recreational marijuana in 2016, but Gov. Paul LePage vetoed the Legislature’s attempt to set up a regulatory framework. An override attempt failed. Lawmakers are expected to try to craft a bill acceptable to the governor during 2018.