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False positive drug tests increase with shifting cannabis laws

On Behalf of | Nov 7, 2019 | Drug Offenses

Scientists say routine drug testing can easily confuse two substances found in cannabis, one that is legal and one that isn’t in most states. The mistaken results have potentially disastrous consequences for people who test positive for the presence of THC.

The chairman of the American Society of Crime Lab Directors expressed concern over labs that might be accidentally mistaking the intoxicating ingredient in marijuana for the legal substance called CBD, which is also found in cannabis.


Hundreds of chemicals found in cannabis can cause drug-like reactions within the body. The two getting the most attention are:

  • THC: Tetrahydrocannabinol is the primary psychoactive ingredient in marijuana and is what makes people feel “high.” The chemical binds with other receptors, especially in the brain, controlling mood and pain and can create a euphoric feeling.
  • CBD: Cannabidiol won’t get you high, but it can work with other elements in the body linked to well-being and is used to help relieve symptoms for arthritis, Crohn’s disease, diabetes and a host of other ailments. CBD became legal in December 2018 as part of the Farm Bill, which legalized hemp.

Standard drug tests cant tell the difference

While CBD causes different reactions in people, its chemical structure has enough in common with THC to produce false positives in common forensic drug tests. As CBD-infused products become more widely available, experts say false positives are likely to increase. In one example, a Florida couple was charged with marijuana possession after a CBD-infused gummy bear tested positive for THC.

Risks will continue, even in states where pot is legal

Illinois is the 11th state to legalize recreational marijuana, and adults 21 and older will be allowed to purchase up to 30 grams starting on Jan. 1, 2020. However, that offers no protection as false positives can still happen for people suspected of “drugged” driving. Drug testing is also allowed for employers, public housing authorities, child service agencies and other entities. If you have been falsely accused of a drug crime, an experienced criminal defense attorney can challenge the accuracy of testing and work to get the charges dropped.