Judy Woodruff:

In the aftermath of the school shooting in Florida, there has been discussion about a number of ways to prevent a repeat of these tragedies, from arming teachers, to stricter gun laws, and addressing people with mental and emotional problems.

But preventing violence by using mental health records is more complicated than many realize. For example, posting a disturbing message on social media doesn't necessarily mean an individual has a mental health concern, and someone treated and diagnosed for a specific illness may never turn up in the federal background check system.

To help us lay this out and look at some of the challenges, I'm joined by Dr. Jeffrey Swanson. He's a professor of psychiatry and behavioral sciences at Duke University.

Professor Swanson, thank you for joining us again on the "NewsHour."

Just to — I want to clarify something going in. You were just reminding us that the vast majority of people who have mental and emotional challenges don't turn out to be violent. Is that right?