Marijuana as a cancer fighting drug? Science says yes, federal law says no. Patricia Crone is caught in the life-and-death stand-off.

Patricia Crone, a professor of Islamic history at the Institute for Advanced Study in Princeton, was diagnosed with lung cancer in November 2011, when the cancer had already spread to her brain. She was busy preparing for the end when she saw that the National Cancer Institute described some of the chemicals in marijuana, or cannabis, as having cancer-fighting potential. With only grim prospects for the future, she wanted to try it.

So Patricia, who had never had as much as a puff of pot, started a hunt for marijuana, and for credible evidence of its medicinal potential. I, Diana C. Frank, Patricia’s sister and a documentary filmmaker, accompanied her all the way, and early on we decided to film the whole odyssey. Twenty-three states allow medical marijuana and four states and the District of Columbia have voted to legalize, but federal law still considers cannabis without medical value and puts it in the same category as heroin. It is a crime to possess it. Because Patricia needed a pound, she risked felony charges.

The clash between science and the law made Patricia’s journey hazardous. but she acquired enough marijuana to start her very own human trial. Over a year Patricia and I traveled everywhere, from university science labs, to a grower in Oregon to actual consultations with her doctors, and get through tense moments as she awaited the results of her brain scans. Forging ahead in a world of hope, obstacles, fear, and contradictions, she rarely lost courage and never her sense of humor. But do the risks she takes prolong her life?