On November 7, 2000, 54% of Colorado voters approved Amendment 20, which amended the State Constitution to allow the use of marijuana in the state for approved patients with written medical consent. Under this law, patients may possess up to 2 ounces of medical marijuana and may cultivate no more than six marijuana plants (no more than three of these mature flowering plants at a time). Patients who are caught with more than this in their possession may argue "affirmative defense of medical necessity" but are not protected under state law with the rights of those who stay within the guidelines set forth by the state. Furthermore, doctors, when making a patient recommendation to the state can recommend the rights to possess additional medicine and grow additional plants, because of the patient's specific medical needs. Conditions recognized for medical marijuana in Colorado include: cachexia; cancer; chronic pain; chronic nervous system disorders; epilepsy and other disorders characterized by seizures; glaucoma; HIV or AIDS; multiple sclerosis and other disorders characterized by muscle spasticity; and nausea. Additionally, patients may not use medical marijuana in public places or in any place where they are in plain view, or in any manner which may endanger others (this includes operating a vehicle or machinery after medicating). Colorado medical marijuana patients cannot fill prescriptions at a pharmacy because under federal law, marijuana is classified as a schedule I drug. Instead, patients may get medicine from a recognized caregiver or a non-state-affiliated club or organization, usually called a dispensary. Dispensaries in Colorado offer a range of marijuana strains with different qualities, as well as various "edibles" or food products that contain marijuana extracts. Certain dispensaries also offer patients seeds and "clones" for those who want to grow their own medicine.