It is difficult to definitively quantify the effect marijuana use has on productivity and safety, but, according to the National Institute on Drug Abuse, part of the National Institutes of Health, studies have suggested links between marijuana use and negative consequences in the workplace, such as a higher risk for injury or accidents. 

Twenty-nine states currently have laws legalizing marijuana for medicinal purposes with an additional eight permitting recreational use of cannabis, including the District of Columbia.

For employers, a growing number of legal cases demonstrates the challenges with maintaining a safe, efficient workforce amidst the increasing number of states that have legalized medical and recreational marijuana.

It happened again just last week. I was at a social event in my Colorado Springs home town, meeting new people and the topic of legalized marijuana came up quickly. 

More states are legalizing medical marijuana, and recreational use is legal in two others. A tangle of federal laws adds to the confusion. Being aware of the legal issues involved and the changing legal landscape is important for employers to ensure that their drug testing policies are legal and enforceable.

Colorado and Washington residents voted to legalize the drug last November and HVAC contractors in both states are examining hiring policies, as well as informing their employees of the dangers and risks of employment under the influence.