Thanks to an April 5 appellate court ruling, medical marijuana is no longer illegal at Arizona colleges and universities, although the campuses can opt to prohibit it. 
Under Arizona’s 2010 medical marijuana law, cardholders are allowed to possess small amounts of cannabis, but people are banned from possessing it in prisons or schools or on school buses. The new ruling in April struck down a 2012 decision by the legislature to expand the prohibition to colleges and universities.
However, if a college or university decides to ban medical cannabis on their campus, they will be within their rights.
In his ruling, Judge Peter Swann wrote that expanding the off-limits list does not “further the purpose” of a law that voters approved at the ballot box, and in some cases “eliminates some of its protections.” 
The state had said that allowing marijuana on campuses would jeopardize federal funding for colleges and universities. However, Swann’s ruling avoids that problem by still giving the state and other landowners the power to regulate which items or materials are brought onto their property. If a student possesses marijuana on a campus where weed is banned, that person could still be removed from the property or charged with trespassing.
“If the state finds it necessary to protect federal funding by prohibiting medical marijuana on public college and university campuses, then the (medical marijuana law) does not stop it from creating such policies. Nor does (the law) prohibit the Legislature from enacting non-criminal statutes to ensure the absence of medical marijuana on college and university campuses.” 
Spokesman Ryan Anderson said that the Arizona attorney general’s office was disappointed with the ruling but hadn’t decided whether to appeal the decision to Arizona’s Supreme Court.
The ruling also overturned a medical marijuana cardholder’s 2015 conviction for having a small amount of weed in his Arizona State University dorm room. Andre Maestas was arrested in 2014 while sitting in a campus intersection and charged with obstructing traffic. When ASU police searched Maestas’ wallet, they discovered his medical marijuana card. , 
Upon questioning, Maestas admitted to having marijuana in his room. The police obtained a warrant to search his room and found far less cannabis than the amount that medical marijuana users are legally allowed to possess. Despite this, Maestas was charged with a felony under the 2012 law, although prosecutors later reduced it to a misdemeanor, meaning he was not entitled to a jury trial.
Maestas was ultimately found guilty, and a judge placed him on unsupervised probation, and imposed a $1,000 fine.
Maestas later appealed.
 Associated Press