Pennsylvania seems to have started pushing towards that in the middle of last year:
"On Aug. 5, the Superior Court of Pennsylvania held for the first time that Pennsylvania's Medical Marijuana Act (MMA) allows an employee to sue his or her employer for taking an adverse employment action based on the employee's status as a certified user of medical marijuana."[1]
"On Aug. 5, the Superior Court of Pennsylvania held for the first time that Pennsylvania's Medical Marijuana Act (MMA) allows an employee to sue his or her employer for taking an adverse employment action based on the employee's status as a certified user of medical marijuana."[1]
1: https://www.shrm.org/resourcesandtools/legal-and-compliance/...