The Depravity Scale is an attempt to reach a scientific definition of evil. What makes a crime “heinous”? If “horrible” or “atrocious” crimes get longer sentences, what counts? The Supreme Court says that sentences must reflect societal attitudes, but right now there’s no legal definition of a “heinous, atrocious, or cruel” act; jurors have to rely on their emotions.

New York forensic psychiatrist Michael Welner put together a list of 26 things that might characterize an act as depraved. Does the criminal maximize the victim’s fear or pain? Does he boast about his act? So far, Welner has found more than 90 percent consensus that 16 of the items indicate depravity. Interestingly, the results seem consistent across states, but not between countries.

“We need consistency, and in particular consistency that reflects the best that forensics has to offer,” Welner says. “From my own vantage point of working within the cases, juries and judges don’t see near as much as they should be seeing when it comes to forensic evidence about what a person’s intent was, what a person actually did, and what a person’s attitude was about what he did. Even from a mental health standpoint, there’s far more effort devoted to the question of who a person is or why that person did something rather than just look at what the person did.”

And Welner has no problem with the concept of evil. “I have no problem with the word being used,” he says. “If you look in the literature, there’s a startling lack of effort to try to flesh out what evil is, and I think it’s our responsibility as behavioral scientists to try to understand it. This issue gets neglected because therapeutic professions like psychiatry inherently must focus on the good in order to be therapeutic. Another reason for this neglect is because to wade in and wrestle with it means to confront it in ourselves, and that’s a painful prospect even for the most stable of us. When I first began exploring this, I never enjoyed it, and I appreciated walking away from it. The more I studied it, the more it affected even my dreams. It’s an unpalatable exercise.”