Currently, there are several factors hindering adoption:
1. Illegal at federal level.
2. No FDA approval. Medical marijuana is not viewed as safe or effective by the U.S. Food & Drug Administration (FDA).
3. Lack of proof of efficacy.
4. Evidence-based guidelines.
5. Effect on work performance.
6. Drug-free workplace programs.
Links
[1] http://www.propertycasualty360.com/2015/07/02/medical-marijuana-a-growing-issue-for-employers-in?page=2&page_all=1
[2] http://www.rethinkpot.org/tags/employer
[3] http://www.rethinkpot.org/tags/workmans-comp