PBS | 9:00 pm

An estimated 55 million Americans say they use cannabis, and that number is expected to grow as voters in more and more states push for legalization. The new episode "The Cannabis Question" explores our relationship with cannabis, uncovering what scientists have discovered about the plant's effects on the body and brain. Though many believe cannabis is benign, even beneficial, confusion reigns as the federal government still classifies it as a Schedule 1 drug, in the same category as heroin.