Over the past 19 years we've gone from exactly zero states having legalized the distribution of marijuana for medical purposes to 23 states and counting that now allow marijuana to be prescribed by physicians to treat various end-of-life ailments (e.g. terminal cancers) and chronic conditions such as glaucoma. Within the past three years we've also seen four states (and Washington D.C.) pass legislation allowing for the legal sale of recreational marijuana.

Marijuana has multiple appeals, depending upon who you ask.

For the consumer, it represents freedom from federal laws, while for the sick it's an opportunity to receive therapy which could improve symptoms. Marijuana is currently being studied in a handful of disease indications ranging from type 2 diabetes to epilepsy.

For individual states, marijuana represents an opportunity to generate revenue through taxation, which could help to fill in budget shortfalls.