The confusion regarding marijuana legalization and the rapidly changing landscape of state-specific laws has created a minefield for employers, says employment law defense attorney Todd R. Wulffson, who recently contributed an in-depth article on the subject. Here are three common mistakes to avoid:

1. Believing marijuana is “legal” and ignoring its potential impact in the workplace. Marijuana is a Schedule I controlled substance under the federal Controlled Substances Act. If you perform federal contracts, have employees working on federal property, or have employees subject to federal regulations (e.g. interstate truck drivers or airline pilots), you have no leeway with cannabis – your employees can never possess it or have any amount in their system. Many states have passed laws protecting individuals from prosecution under state law if they grow or possess a small amount of marijuana. One of the biggest mistakes an employer can make, however, is believing these state laws reduce potential liability for the bad acts of a stoned employee. Cannabis impairs judgment, and this is exacerbated when someone is driving or operating machinery. People under the influence also have a tendency to lose their internal filters and inhibitions and may say or do things that can lead to discrimination or retaliation claims.
2. Not keeping up with cannabis laws in your state. The risk of serious liability associated with cannabis intoxication at work leads many employers to want to adopt a “zero tolerance” policy with regard to drug testing employees (i.e. any THC in one’s system is grounds for discharge). It is fine – everywhere – to have a policy that says employees cannot possess, use or be under the influence of THC on company property or on working time – but the “under the influence” part is subject to state law. Similar to alcohol – where legal intoxication is at a blood alcohol level of .08% – many states have determined when a person is deemed “intoxicated” from cannabis. State laws vary widely, so employers need to be familiar with the specifics.
3. Not updating your policies and procedures. One of the most avoidable mistakes employers can make is failing to update their policies to reflect the changing cannabis legal landscape. For example, most employers have a policy that says the company conducts drug testing to ensure applicants and employees are not under the influence of “illegal” drugs at work. Employers do this to put applicants and employees on notice of testing that would otherwise be an invasion of their privacy. Savvy applicants or employees who may have lost an employment opportunity because of that policy may argue that they failed the test because of a “legal” drug and that they did not give consent to be tested for cannabis. To avoid this potential problem, employers should update their drug testing policy to define an “illegal” drug as including improper use of prescription or over-the-counter drugs, as well as “all forms of marijuana and any product containing THC.” Other examples of necessary policy and procedure updates may include smoking policies and manager training procedures.

One of the biggest issues with the constantly changing cannabis laws is that even though cannabis is still considered illegal at the federal level, many states have legalized it to some extent, says Director of HR Sue Schwartz.

Employers will need to check in the state in which they work, but in Florida, a drug-free workplace policy (DFWP) can still supersede a medical marijuana card.

Also, the Americans With Disabilities Act may require reasonable accommodations for employees if they do not create a hardship for the business and for certain medical conditions but Florida law does not include medical marijuana as a qualifying accommodation.

To use the DFWP policy, it needs to be very clear and posted conspicuously. It should be included in the employee manual so that they sign for it and in the new hire package, again with a sign-off that they have received it.  The employer also needs to have a defined testing protocol like pre-employment, post-accident, etc.

Employers need to stay abreast of changing laws regarding the cannabis industry, according to HR Leader Erin ImHof.

What is legal in one state or municipality may not be legal in another. They should consult with trusted counsel or an HR team and update policies accordingly as laws change.