Can a work place refuse to hire me because I have a medical marijuana liscence and I cant pass a drug test?

I wonder if that falls under a type of discrimination? I have had my medical marijuana prescription for a year, and was told by a company that the will not hire me because I use medical marijuana. I only smoke at night and never during the day, so I will never go to work high, and they still refuse to hire me.

: http://alcoholdrugstreatment.info/can-a-work-place-refuse-to-hire-me-because-i-have-a-medical-marijuana-liscence-and-i-cant-pass-a-drug-test