Brains on Trial

By: Laurence Steinberg, Ph.D.

In 2005, the United States Supreme Court, in Roper v. Simmons, abolished the juvenile death penalty. Roper is one of the most important cases about young people ever decided by the court, not because it directly affected a large number of teenagers, but because of the way in which the science of adolescence informed the majority's thinking. Drawing from the latest research on psychological development in adolescence, Justice Anthony Kennedy, who wrote the majority opinion, opined that people under the age of 18 are inherently less blameworthy than adults due to their psychological immaturity. Because of this, minors should not be exposed to the punishments we reserve for adults who are fully responsible for their acts. Between 2005 and 2016, the court issued rulings in multiple cases that built on the logic of the Roper decision, banning the use of life without the possibility of parole as a sentence for juveniles convicted of crimes other than homicide, prohibiting states from mandating life without parole for juveniles convicted of homicide, and noting that the "reasonable person" standard that is often applied in evaluating someone's decision-making needs to be adjusted to take into account the fact that adolescents' judgment is not as sophisticated as that of adults.

Roper wasn't the first time the Supreme Court ruled that adolescents are different from adults in legally relevant ways, but it was the first time that the court looked to science rather than common sense to reach this conclusion. And some of the science that the court looked to in reaching its decisions in Roper (and the cases that followed) was conducted at Temple University's Psychology Department. For the past 20 years, I have been involved in a program of research designed to elucidate the ways in which adolescent judgment and decision-making differ from that of adults. Much of the research has been done in collaboration with Professor Jason Chein, a cognitive neuroscientist who specializes in the study of high-level cognitive function, and with the assistance of our team of undergraduates, graduate students and postdoctoral fellows. Jason and I have been trying to understand why adolescents are so much more likely to take risks when they are in groups than when they are alone. This research has important legal implications because adolescents are far more likely than adults to commit crimes in groups.

I have been active in bringing the results of this work to the attention of lawmakers, legal practitioners and the popular media. I've been consulted by defense attorneys across the country and have testified in numerous court cases involving juvenile defendants who are awaiting sentencing. In recent months, I've taken the stand in several cases in which the defendant was slightly older than 18, in light of new evidence showing that the brain continues to mature after this age and that this maturation leads to improvements in self-control. For example, in a recent study we completed in 11 countries in Africa, Asia, Europe, the Middle East, and North and South America, we found that individuals' ability to exercise impulse control—an important consideration in many criminal cases—continues to mature until at least 22. So far, courts appear to be sympathetic to the idea that the logic of Roper can be extended to cases involving people up to the age of 21. Given what is taking place in courts around the country, there is a very good chance that within the next five years, the Supreme Court will have to rule on this issue.