Will Neuroscience Radically Transform the Legal System?
Brain scans may help us read minds and assign responsibility better.
Photograph by Miguel Medina/AFP/Getty Images.
This article arises from Future Tense, a partnership of Slate, the New America Foundation, and Arizona State University that explores emerging technologies and their implications for public policy and for society. On Monday, Oct. 22, Future Tense will host “My Brain Made Me Do It,” an event in Washington, D.C., on how the legal system will adapt to changes in neuroscience. For more information and to RSVP, or to watch the live stream, visit the New America Foundation’s website.
Although academic fields will often enjoy more than Andy Warhol’s famous 15 minutes of fame, they too are subject to today’s ever-hungry machinery of hype. Like people, bands, diets, and everything else, a field gets discovered, plucked from obscurity, thrown into the spotlight, and quickly replaced as it becomes yesterday’s news.
Neuroscience is now the popular plat de jour, or, perhaps better, the prefix de jour, and neurolaw is one of the main beneficiaries—and victims. Neuroscience will have important and even dramatic effects on our society and, as a result, on our laws. But not yet, and not as dramatically as some envision.
First, consider timing. Many of the most interesting neuroscience results come from functional magnetic resonance imaging (fMRI). This technique allows us to see what parts of the brain are working and when, and thus to begin to correlate subjective mental states with physical brain states. The use of fMRI on humans goes back about 15 years, and although about 5,000 peer-reviewed scientific articles involving fMRI will be published this year, we are still trying to figure out how it works—or doesn’t. The fMRI results showing apparently purposeful brain activity in dead salmon are a wonderfully funny example of some of the limits of this technology, and fMRI is one of the oldest of the “new” neuroscience technologies. Half of what neuroscience is teaching us about human brain function will be shown, in the next 20 years, to be wrong—and we will need each of those 20 years to figure out which half.
But, second, we need a sense of proportion. Neuroscience will provide tools that will change the law in some important ways, but those tools will be neither perfect nor used in isolation, and those changes are not likely to strike at the law’s roots.
For example, neuroimaging will be able to read minds—to some extent. A scanner may be able to tell whether I am hungry and even whether I want a burger. Without my cooperation, it will not know that I want a bacon cheeseburger, hold the mayo and mustard, extra ketchup. Similarly, it can never know what I was thinking three months ago or, with certainty, what I will be thinking three months from now.
Plus, neuroscience is likely to be used in conjunction with behavioral evidence. Typically, the best way to know what someone wants to do is to see what she does. Neuroscience will rarely make usable findings about, say, competence to stand trial or insanity, without evidence about the person’s actual behavior. Normally, it will provide just one piece of the puzzle and not a magic key.
Finally, law is not going to disappear because of neuroscience. Getting a better handle on what brain machinery causes certain behaviors will change the criminal justice system, but it will not make it dry up and blow away. Neuroscience evidence of mental state may ultimately be admitted in trials, but it will not restrict the roles of judges and juries to reading brain scans. The most extreme outcomes are the most interesting—as science fiction and in the popular media —but they are not the most likely.
After all this talk about what neuroscience will not do, what is left? Quite a lot, I think, in five different categories: prediction, mind-reading, responsibility, “treatment,” and enhancement.
Neuroscience will help us predict future mental states or behaviors, usually not alone and not perfectly, but usefully. And these will lead to legal issues. When we can accurately predict which 60-year-olds are going to be diagnosed with Alzheimer’s disease in the next 15 years, those predictions will affect, among other things, employment, insurance, guardianships, financial planning, and Medicaid. If we could tell which roughly one 15-year-old in 100 will be diagnosed with schizophrenia, to what ends would we want, or allow, those predictions to be used? Or what about good predictions of who is going to commit violent crimes, either after conviction or before? We already use psychology, demographics, and personal history to make such predictions—what will we do if neuroscience can greatly improve those predictions?
Henry T. Greely is the Deane F. and Kate Edelman Johnson professor of Law, a professor by courtesy of genetics, and director of the Center for Law and the Biosciences at Stanford University.