After waiting in line for hours at a booth during a medical marijuana convention in San Francisco, Jeff Harrington needed only a two-minute consultation and a written recommendation to become a medical marijuana patient in California. He now can legally purchase and possess marijuana from any one of thousands of marijuana businesses in the state.

Across the country in Connecticut, an established physician-patient relationship is required before patients are deemed qualified for medical marijuana, and only licensed pharmacists can own and operate dispensaries.

Between these two extremes, a News21 investigation has found there are as many ways to deal with medical marijuana as there are states that have legalized it. News21 is a Carnegie-Knight national student reporting project based at Arizona State University’s Walter Cronkite School of Journalism.

As the federal government continues its prohibition of marijuana, the District of Columbia and the 23 states that have legalized marijuana for medical use have been...