Frequently asked questions Colorado Medical Marijuana History & Laws – Overview 2000 – Voters approve Ballot Amendment 20, removing state-level penalties on use, possession and cultivation of cannabis by those with a valid recommendation from their physician. 2010 – Governor Bill Ritter signs House Bill 1284 (HB 1284) and Senate Bill 109 (SB 109). HB 1284 regulates dispensaries, whilst SB 109 ensures that doctors conduct a proper physical examination and that they do not have a DEA flag on their license. Recreational marijuana is legal in Colorado. Medical marijuana patients may possess up to 2 ounces, and for those without a valid recommendation and card the possession limit is up to 1 ounce. There is no penalty for giving another a person an ounce or less, providing no money changes hands and the people giving and taking the cannabis are aged 21 or over. Medical marijuana patients must be aged 18 or older to apply for themselves. Recreational cannabis users must be aged 21 or over. Both medical marijuana patients and recreational cannabis users may grow up to 6 cannabis plants, with no more than 3 mature plants at any one time. Possession of 8 ounces or more will be considered possession with the intent to distribute. There is no penalty to possess up to 1 ounce of hash or concentrates.