Doris Foster sits in an armchair in the living room of her unit at an independent living facility. The armchair next to her is empty.

Doris Foster has pain in her knees caused by pinched nerves in her lower back. Foster, 94, takes drops of hemp oil on her tongue from a strain of marijuana with none of the psychoactive THC, but is high in Cannabidiol (CBD). This allows her to benefit from the pain relief of medical marijuana without experiencing the typical effects associated with a smoker's high. Foster lives in an independent living facility in Boulder, Colo., and has had her medical marijuana license for five months.