Many colleges forbid medical marijuana use by their students despite state laws allowing it, and students are beginning to challenge their policies. Typically, college policies state that students with a legal medical marijuana license are not allowed to use cannabis, so students are left to either not use cannabis or secretly medicate themselves and worry about the potential consequences, like expulsion.

One student is suing GateWay Community College in Phoenix for expelling her for violating the school’s drug policy, according to the Washington Post. School officials pulled her out of class to conduct a drug test. The student, who was studying diagnostic medical sonography, uses cannabis for chronic pain from polycystic ovary syndrome. Actual drug testing is more common in nursing and medical programs.

Colleges fear losing federal funding if they don’t abide by federal law. According to USA Today, some states, like Connecticut, have addressed this grey area by forbidding colleges to discriminate against students who use cannabis.