The approval of Proposition 215 in 1996 saw California become the first US state to legalize medical cannabis use. Nearly three decades later, 21 states have fully legalized marijuana use, with 37 approving medical marijuana programs.

Marijuana use exploded with the passing of Proposition 64: The Adult Use of Marijuana Act in California in 2016. The drug was rapidly adopted across the country, including in the nation’s capital, Washington, DC. With more people using marijuana in flower, concentrate, and edible products, it’s becoming a problem for employers to find employees that don’t use the drug, especially in states with full legalization.

Many people using cannabis in states where it’s legal assume they can arrive at work high, and their employer can do nothing to reprimand them. Since it’s so challenging to prove when a person last used the drug, there’s little employers can do to fire or discipline a blatantly high worker.

However, that’s not always the case. Some employers may have the right to a drug test and polygraph their staff if they think they’re high on the job. This post unpacks the legality and methodology behind polygraph exams and drug testing to oust employees who use cannabis on the job or arrive at work high.


The Legality of Marijuana Use in the Workplace – The State of the Nation

In some states in America, employment is still “at will,” meaning the employer can fire the employee without just cause for their decision. Businesses operating in the private sector in these states can fire employees for using cannabis on the job or arriving high at work, regardless of the state or Federal law surrounding the legality of cannabis use.

Some states across America also provide employers with “outs” for releasing employees they suspect or confirm use cannabis at work or arrive at work high. For instance, the Proposition 64 legislation in California, which legalized adult marijuana use, says that state employers can penalize employees who test positive for the drug.

It’s also important to note that cannabis is still illegal at a Federal level. So, employees working in Federal agencies, such as the FBI or US Justice Department, and those workers employed in Federally regulated industries, such as banking, transportation, and health care, are legally prohibited from using cannabis, even outside of work on their downtime.

Employers in the private sector should stay on top of changes in legislation in their state. This includes the laws surrounding cannabis use and drug testing. Companies operating in states where cannabis use is legal for medicinal or recreational purposes should consult with legal counsel before taking action against employees for cannabis use.

Notably, 10 states have “compassionate care” statutes allowing the medical use of cannabis. Under this law, employers cannot disqualify employees or candidates from work because they test positive for cannabis.

37 US states allow the use of medical or recreational (or both) cannabis. However, most of these states allow employers to fire employees or deny candidates a job for using marijuana in their downtime away from work.

As a result, advocates of cannabis legislation want the government to do more to protect workers’ rights with regard to cannabis use. These advocates note that employers using workplace drug tests cannot determine if the employee is high at the time of the test.

These proponents of cannabis legislation also state drug testing in the workplace is an equity issue since testing programs are more common in companies offering blue-collar jobs, disproportionately affecting POC workers.

As of 2023, 14 states, including Washington, DC, banned employers from discriminating against those workers who use medical cannabis to treat a diagnosed condition. New York and New Jersey prohibit employers from discriminating against their workers who use cannabis legally for medical or recreational purposes.

Nevada bans the refusal of employers to hire candidates that test positive for cannabis. However, it’s important to note there are exemptions to these laws for some industries and occupations.


The Legality of Marijuana Testing for Employees

Companies that employ regulated employees, such as school bus drivers and airline pilots, and Federal contractors must test their employees for cannabis use. Other employers have the choice of instituting testing policies or leaving them.

Some companies might decide to test their workers as part of their employment application, after an incident at work, or randomly if they suspect an employee is high at work. Most of the biggest employers in America currently have some form of drug testing program for employees.

According to research, around 75% of workplace drug tests are from pre-employment screening programs. The data suggest drug testing programs for employee or candidate cannabis use are becoming less common across all states. Similarly, the number of urinalysis screenings for workplace cannabis use declined by 5% between 2015 and 2020.

Most of the legislative arguments surrounding cannabis use in the workplace and drug testing experience challenges with how to measure cannabis intoxication and workplace safety. With the current state of affairs surrounding these issues, there seems to be no solution to the problem coming any time soon.

There is no breathalyzer test available for cannabis use and no legal limit set for “unsafe” levels of cannabinoids in a worker’s bloodstream. No current drug test can measure the impairment of a subject or their frequency of use of the drug.

Proponents of cannabis legalization point out that cannabinoids (the active compounds like THC found in marijuana) may linger in the bloodstream for weeks after a person uses cannabis. So, we can think of failing a marijuana drug test in the same context as being caught for a beer you had three weeks ago.


Understanding Medical Marijuana Use

39 states, including the District of Columbia, legalized the use of medical cannabis as of 2023. These states allow people to register as patients and receive a medical cannabis card, provided they receive a diagnosis from a qualifying medical professional who authorizes their treatment.

While medical cannabis is still illegal under Federal law, state law officials will not prosecute medical cannabis users. Over a dozen of these states—including Massachusetts, Illinois, Delaware, and Arizona, offer employee protections for the use of medical marijuana.

Employers operating in these states may not fire their employees or discriminate against cannabis if they’re legally registered medical cannabis users. The same applies to those employees who test positive for marijuana on a drug test. The state provides protection for these employees who use cannabis outside of work hours.

However, employers may fire these employees if they are under the influence of cannabis and impaired on the job. This legislation doesn’t prohibit employers from discriminating against medical cannabis patients when complying with Federal requirements, such as for a requirement of receiving Federal funding.

Other states with medical cannabis laws expressly allow employers to fire their employees for cannabis use outside of work, or the states don’t have any regulations addressing the issue. However, the courts will usually side with the employers in these cases.


The Rules Surrounding Improper Drug Testing of Employees

The legislation covered previously assumes the employee tests positive for cannabis in a legally administered drug test. If the test violates the law, the employer may not fire the employee based on the test results.

Federal law protects employees who take prescription medications to treat a disability, and many states have legislation covering how the employer can conduct a legal drug test. Typically, employers get more leeway in a candidate than employee testing.

Employers are usually free to drug test candidates routinely after making an offer of employment. However, some states do not allow employers to conduct random or routine testing of employees who already work for the company.

Instead, the employer requires a reason to test the employee, with the following providing legal grounds for administering the test.

  • An employee appears impaired at work.
  • The employee is involved in a workplace accident resulting in property damage or injury to others.
  • The employee returns to work after completing a rehab program.
  • The employee holds a position at the company that’s safety-sensitive.

Even if the employer has the legal right to drug test the employee, they must follow the proper protocol for administering the test. The following are some of the guidelines for legal drug testing by employers.

  • The employer must provide the candidate or employee with advanced notice of their intention to test them.
  • The company must use a state-certified lab for the test analysis.
  • The company must foot the testing costs.
  • The company must give the employee a chance to challenge the test results if they fail.
  • The company must administer the drug test in a manner that minimizes an intrusion on their privacy.


Can an Employer Request a Polygraph for Suspected Cannabis Use in the Workplace?

As mentioned, one of the issues with uncovering cannabis use in the workplace is that the drug test cannot pinpoint if the user is under the influence of marijuana or when they last used the drug. In this case, the polygraph can play a vital role in proving if the employee was using the drug at work.

By polygraphing the employee, the examiner can ask the employee if they’ve ever used cannabis at work or if they’ve ever arrived at work high. Suppose the polygraph corroborates the results of the drug test. In that case, the employer can argue that it proves grounds for dismissal, depending on the state laws surrounding cannabis use and employment law.

However, is it legal to polygraph an employee suspected of using cannabis in the workplace or arriving at work high on the drug?


Understanding the Employee Polygraph Protection Act

The “Employee Polygraph Protection Act of 1988” (EPPA) is blanket legislation protecting employees across America from employer abuse of polygraph policies in the workplace. The Act states that employers may not use polygraphs on candidates or employees in the hiring or firing process.

However, there are exemptions in this legislation. For instance, if the employer suspects drug use in the workplace or their employee is doing their job while high, they can institute a polygraph policy and test the employee.

Provided the employer consults with an attorney and uses an external polygraph company to conduct the test, they have the right to request their employees to take a polygraph exam. However, it’s important to note that the EPPA provides protection for the employee, even with the implementation of this exemption.

The EPPA states that the employee has the right to refuse to take the polygraph exam. If they do evoke this right to refusal, there is nothing the employer can do to take disciplinary action against them. They may not fire them, and they can’t reprimand the employee in any manner for refusing to take the test.


Can an Employer Use Polygraph Results as Grounds to Fire Me for Cannabis Use?

If the employee does consent to the test, which is highly improbable if they’re guilty of the violation, the employer can use a failed drug test result in corroboration with the failed polygraph result to provide grounds for dismissal of the employee. A failed polygraph result alone is insufficient grounds for dismissal, as it’s against the EPPA legislation.


What Happens if the Employer Violates the EPPA?

The US Labor Department enforces the EPPA, and they take it seriously. Suppose the employer violates the EPPA and polygraphs the employee without following the necessary procedures outlined in the Act. In that case, they face an investigation into the matter by the US Labor Department and stiff financial penalties if the investigation proves misconduct.

If employees feel their employer violated their rights, they can contact the US Labor Department directly to file a complaint against them. Alternatively, they can hire a lawyer to handle the filing and due process involved with the complaint.

For this reason, the employer must follow all EPPA guidelines when implementing a workplace polygraph policy. They must hire a competent and experienced labor attorney and a qualified, certified, and approved external polygraph firm to handle the test and assist with compiling and executing the polygraph policy.