Why It's Hard To Prove Someone Not Guilty By Reason of Insanity

At the trial of James Holmes, who opened fire in a movie theater in Aurora, Colo., in 2012, the prosecution is turning to examine Holmes' state of mind at the time of the shooting. He's pleaded not guilty by reason of insanity to 166 criminal counts, including first degree murder.

How hard is it to make that case? Experts say this may be the first time a jury has ever had to consider the insanity defense in a death penalty case in Colorado.

Here & Now's Robin Young discusses this with Christopher Slobogin, director of the criminal justice program at Vanderbilt University Law School, and associate professor of psychiatry at Vanderbilt University School of Medicine.