Must we change our drug policies in light of the legalization of marijuana use?

Q: “With proposition 207 that passed in Arizona for use of recreational marijuana, I was wondering as a construction company that’s safety-sensitive, will we also have to adjust our drug policies since it is legal for recreational use? Can I still deny employment to an applicant who failed to pass a drug test but has a medical marijuana card since all of the positions I have are safety-sensitive positions?” – Dafra, Arizona