- In 2010, Arizona became the 15th US state to legalize medical marijuana through the passage of Proposition 203. This made Arizona the most recent state to recognize cannabis' therapeutic benefits. - The Arizona Department of Health Services is currently developing the rules and regulations for the distribution and use of medical marijuana in Arizona. - Despite ongoing federal restrictions, many states have passed their own medical marijuana laws, with Arizona being the most recent. Patients are protected from state prosecution in states that have legalized medical cannabis, but not federal prosecution.