Brain Science and the Law

by Nicky Penttila

March 18, 2011

While neuroscience can tell us a lot about how the brain works, it has not yet produced much data that can be used to decide criminal or civil disputes. But that hasn't stopped lawyers from trying to enter it as evidence, said presenters during a two-day Law & the Brain conference called held in New York this week.

"Neuroscience is concerned with observable, objective phenomena that occur in the brain, but law is often concerned with unobservable, subjective states of mind," said Jed Rakoff, U.S. district judge for the southern district of New York. To use the knowledge gained by brain research in applying the law "requires a mediation of language that is just starting to be developed," he said. Cognitive neuroscience, the study of how the brain produces thought, could help build such a shared language, but it is "still an infant science," he said. "There is a great danger, I think, in terms of using it in the law."

But the law isn't waiting. By 2008, neuroscience data already had been introduced in legal cases 584 times, according to one review, Rakoff said. "The science isn't there, but it comes in anyway," he said.

"This is incredibly tantalizing work," said researcher Michael Gazzaniga, often called the father of cognitive neuroscience. What scientists are learning about impulsivity in juveniles and how psychopaths differ from the norm are two examples of how research "will influence how we think about ourselves," Gazzaniga said, including our notions of free will and justice. Today, though, "it's probably of little or no use" legally, he told the more than 120 attorneys, judges, law professors, psychologists, and others attending the conference. The arguments "are waiting for science to come up with greater specificity."

For example, because people's brains vary so much, most brain imaging studies combine their research subjects' data and show the average results. In court, though, the question is usually about a single individual and his or her specific state of mind at an exact moment in time; the average can't tell us much about that. Averaged research about how the brain develops was cited, though, in the Supreme Court's decision to strike down the death penalty for juvenile offenders, a decision about a class of people.

One area of great interest to the law is pain. In injury lawsuits, disability hearings, and criminal cases, how much pain a person suffered or still suffers is important to determine—but impossible to see from the outside. "We're obviously not very good at doing this now," said Adam Kolber, a professor at Brooklyn Law School who also founded the Neuroethics & Law blog. "And if we wait until the technology is perfect, we'll never get there. The question is, will the technology get us closer than we're getting now?"

We may be getting close now on measures of chronic pain, Kolber suggested, citing research that shows that chronic pain over time leads to structural changes in the brain. "It's hard to fake the structure of your brain."

Another area of interest is memory: How well do people remember, especially in emotionally charged situations? Not as well as they think, said forensic psychologist Elizabeth Loftus of University of California, Irvine. "We know from the hundreds of wrongful-conviction cases that mistakes do happen," she said.

She showed audience members a series of different faces, and then asked questions, putting a similar-but-not-the-same face in the mix. When later asked to identify the remembered the first set of faces, about one-third of the audience got it wrong. "All that IQ, all that education, all that experience, it doesn't protect you from false memories," she said.

Loftus has testified in several cases that involved "repressed memory," and started doing research to see how easily memories could be modified or created from whole cloth. Some of her recent research into "rich false memories" include implanting the idea that a person had an especially terrifying day at the mall when a child or that she has always hated strawberry ice cream simply by using the power of suggestion. The majority of her subjects resisted the implanting, but some not only accepted it but added details to embellish the memory.

"People felt just as emotional about their false memories as they did for their true memories," Loftus said. "Emotion is no guarantee of memory accuracy."

Psychologist Elizabeth Phelps of New York University also studies emotion's effect on memory. "Memory is not a tape recorder, it's a reconstructed story," she said, and emotion can color what we choose to focus on, what we retain, and what we retrieve when calling up a memory.

Many studies suggest that the most vivid autobiographical memories are usually emotional events; they are recalled more often and with more detail than emotionally neutral events. But are those details always right?

On September 12, 2001, researchers asked Duke students to record their memories of first hearing about the attacks the day before and of a recent everyday event; a few weeks to a few months later, they were again asked to record those memories. Their accuracy for both events declined in a similar way, but their belief about their accuracy differed: The students were sure they remembered the attack details exactly right. This research, reported by Jennifer Talarico and David Rubin (PDF), replicated results from a study in 1992 (PDF) about people's memories of the Challenger explosion.

"Most people, including me, believe we have better memories for highly emotional events," Phelps said. "I don't believe I'm wrong, either, I just know the data say I'm mistaken."

When people recall events "we shouldn't expect complete, unbiased accuracy," she concluded. "And confidence in memory is not a measure of accuracy." This drew a chuckle from the audience. Witness testimony is one of the bases of the legal process.

As with other findings in brain science, what we currently know about memory is nowhere near exhaustive. One question to pursue, Phelps said, is whether trained professionals such as police or EMTs might hold memories more accurately because they are less emotionally charged than those of other witnesses. How might chronic emotional conditions, such as depression, color or clear our memories? And how do our unconscious biases affect what we focus on and what we recall?

"It's not too soon to begin thinking about these issues," Judge Rakoff said.

The Dana Alliance for Brain Initiatives was one of the sponsors of the Law & the Brain event. Presenters Michael Gazzaniga, Abigail Beard, Martha Farah, and Elizabeth Phelps are members of the Dana Alliance; moderator Edward Rover is chairman of the Dana Foundation.


An earlier version of this story gave an incorrect link to research by Susan Wolf. We apologize for the error.