Here are the key Slides/Statistics he used which document the shocking increase in the numbers of Americans incarcerated in recent decades and the percentage of these who are incarcerated for drug offenses and mental illness:
Here is an audio link to his NPR (National Public Radio) Interview from Sunday March 29, 2009:
http://www.npr.org/templates/story/story.php?storyId=102486450
http://www.parade.com/news/2009/03/why-we-must-fix-our-prisons.html?index=2