Employers often use a five-panel drug test to screen for amphetamines, cocaine, marijuana, opiates, and phencyclidine (PCP). However, some employers have removed marijuana from the panel. Urinalysis is the most common screening method used by employers as it is relatively inexpensive, rapid, and non-invasive. It can detect the use of illicit or prescription drugs. The downside to urinalysis is that it only detects recent marijuana use.
THC, the chemical that produces the psychoactive effects of marijuana, can stay in the body for up to several weeks. This means that a positive result does not necessarily indicate current impairment or frequency of use. So, if an employee is an occasional marijuana user on a rare weekend, does that affect their overall ability to do their job?If an employee is visibly impaired on the job or possesses marijuana on the job, an employer could test and sanction them. A New York City law will soon prohibit many employers from taking any pre-employment marijuana test, and a Nevada law now prohibits employers from taking adverse action based on a positive pre-employment marijuana test result.
Paul Armentano, deputy director of NORML, told Marijuana Moment that “random marijuana testing in the workplace, such as pre-employment drug screening, has never been an evidence-based policy.” Since there is no device that can test for active impairment and tests for THC metabolites can show traces of marijuana for weeks after a person uses marijuana, employers must demonstrate that a given worker “manifests specific articulable symptoms of impairment” in order to punish them for using marijuana on the job. However, certain employers are required to test for marijuana under federal law as the federal government classifies marijuana as a dangerous drug similar to heroin. Additionally, other employers may want to make sure they don't employ drug users who may threaten workplace safety.