The federal government says there is no such thing as “medical” marijuana. Despite that, an increasing number of states have legalized the use of marijuana for medicinal purposes, and a couple, so far, have okayed recreational use of marijuana for adults.

In the medical context, doctors often prescribe marijuana to manage chronic pain, and those patients must register in a confidential patient database. Registration triggers issuance of registry identification cards so recipients avoid criminal liability. Because many such patients are in the workforce, however, employers need to be aware of existing medical marijuana laws and pending legislation in each state where they employ workers.