State laws authorizing use of marijuana for medical purposes have resulted in a series of employment lawsuits testing the boundaries of employees’ rights to use the drug off-duty.

So far the courts have upheld an employer’s right to fire employees who test positive for marijuana, even if the employee has a card authorizing him to use marijuana for a medical condition. But the issue raises liability concerns that are growing as more states pass medical marijuana laws.

Beyond the 14 states where possession of marijuana is already legal for certain medical purposes, several other states are considering laws that would legalize cannabis.

A bill called the Compassionate Use of Medical Cannabis Pilot Program Act is pending in both houses of Illinois’ legislature. The bill would permit individuals diagnosed with a “debilitating medical condition” to obtain a registration card and possess small amounts of cannabis for personal use.

Likewise, Tennessee’s H.B. 2562 would allow patients to use medical marijuana if they are diagnosed with a specific list of ailments: cancer, Hepatitis-C, multiple sclerosis, epilepsy, glaucoma, chronic pain, severe nausea, Crohn’s disease, Alzheimer’s, and Lou Gehrig’s disease.

Bills related to loosening restrictions on medical use of cannabis are also pending in Alabama, Delaware, Iowa, Kansas, Maryland, Massachusetts, Missouri, New York, North Carolina, Pennsylvania, South Dakota and Wisconsin.