As medical marijuana becomes more common in Colorado, landlords increasingly are encountering tenants who are using and growing marijuana. Under state law, a person who has a medical need can possess up to 2 ounces of the drug. Someone can also possess up to 6 marijuana plants.  But who--and which law--has the final say when a certified user lives in a rented property? Can they smoke and grow at home? For answers, we turn to Drew Hamrick of the Denver law firm Coldiron and Hamrick, which represents landlords.