Professor Judith Edersheim delivered the 2026 Weaver Program Distinguished Lecture on the intersection of neuroscience and law, titled Defeating Brain Myths in the Courtroom: From Nonsense to Neuroscience. Dr. Edersheim is an assistant professor of psychiatry at Harvard Medical School and founding co-director of the Massachusetts General Hospital Center for Law, Brain and Behavior, where she is an attending psychiatrist. She holds a J.D. and an M.D. from Harvard University and has extensive experience in mental health forensics in criminal and civil contexts, including evaluations of transactional capacity and criminal responsibility. Dr. Edersheim’s lecture explored how outdated assumptions about human cognition and emotion persist in legal doctrine, producing unjust outcomes. 
The “Reasonable Man” Standard in Law
Dr. Edersheim spotlighted a longstanding yet misrepresentative benchmark in legal doctrine. The construct of the “reasonable man,” she explained, is introduced early in legal education, embedded throughout legal reasoning, and used to define the boundaries of acceptable conduct.
“The law has a herculean task, and that task is actually to regulate all of social and political life,” she said. “Well, how would you do that? You would decide how the average, solid citizen should behave in a civil society, and you would punish deviations from that behavior.” She explained that “negligence is, of course, the failure to do what a reasonable man would do. Defamation is something that would make the reasonable man think less of you. Foreseeability is only as far as the reasonable man can foresee.”
The reasonable man standard relies on a model of human cognition that modern neuroscience challenges, Edersheim argued. It presumes that the reasonable person possesses a stable and rational mind—unaffected by age, experience, culture, or varying cognitive ability. Through the development of imaging technology, neuroscientists have made discoveries that discredit this model. “[Brains] don’t always operate independent of age or experience or emotion, and to pretend otherwise actually causes fundamental injustices in legal doctrine,” she explained. She cited several examples, including juveniles and people experiencing mental illnesses, substance use disorders, cognitive decline, and neurologic illness.
Debunking Classical Emotion Theory
Conventional views of reasonable behavior create myths in emotion neuroscience, Edersheim contended, and these myths distort legal outcomes. The law follows a classical model, holding that emotions are hardwired and expressed through universal cues such as facial expressions and demeanor.
“Much of how we portray human beings in the legal system is actually anchored in this classical theory of emotion,” she explained. “We expect jurors, for example, to judge the credibility of witnesses by their demeanor, their expressions, their diction. We actually instruct judges to use external cues and their own life experiences to detect sincerity and remorse in defendants—conclusions that really matter for triage for sentencing.”
Dr. Edersheim argued that, like the concept of the reasonable man, this theory is “complete fiction.”
“No psychologist, no neuroscientist, no psychiatrist has believed this for 30 years, at least. And this really matters when we evaluate the legal system.”
Crediting Professor Lisa Feldman Barrett – a leader in neuroscience and discoveries on emotion formation – Dr. Edersheim emphasized that emotions are not located in specialized brain regions, are not automatically triggered, and are not universally expressed across individuals. Instead, emotions are constructed by sensory and visual input, introspective cues, and personal history, culture, and memory. Interpretations of emotion are shaped by the observer; therefore, the law’s reliance on external cues to read emotion is fundamentally flawed.
“The emotions that you think you’re detecting in other people are actually coming from inside your head, not theirs,” Dr. Edersheim said. “Trying to identify the meaning of someone else’s emotions using an external representation, like a facial expression, a body signal, a posture, or even a neuronal signal, isn’t possible.”
Challenging Emotion Reading in Court: The Case of Melissa Lucio
Edersheim discussed the case of Melissa Lucio, who is on death row in Texas for the 2008 death of her two-year-old daughter, who died from a fall down the back stairs of their apartment. Lucio, who had a history of being abused, was convicted following a six-hour interrogation conducted immediately after the child’s death; during questioning, she was unrepresented and traumatized in a coercive environment. Central to the trial was testimony from a Texas Ranger who claimed that it was “clear as black and white that her facial expressions, her posture and her demeanor, and her failure to stand up to him were clear and certain indicia of guilt.”
“He highlighted his vast experience in reading emotions,” Edersheim said. “He highlighted his experience as a police officer and how that made him an expert in this field.”
Six weeks before the scheduled execution, a scientific team—including Dr. Edersheim, Barrett, and The Innocence Project—submitted two briefs denouncing the interrogation and scientifically baseless evidence presented in Lucio’s trial. They argued that “emotion reading isn’t a thing, and that the premise of this interrogation and testimony was based on junk science,” and “if it’s not a thing, you can’t be an expert.” Following another examination of the evidence, the judge vacated Lucio’s conviction and death sentence, citing that the ranger’s testimony was false. Lucio remains on death row, her case pending at the Texas Court of Criminal Appeals.
Dr. Edersheim said, “The judge’s opinion actually quoted from our brief: ‘Ranger Escalon’s statements that he was able to determine applicant’s internal thoughts and emotions from her facial movements, body posture, and diction in the interrogation room after her daughter’s death is scientifically baseless and false. Scientists have established that there is no single template, fingerprint, or signature of physical signs that express guilt or innocence across all individuals in every culture.’”
Expanding Access to Research on Neuroscience and Law
Dr. Edersheim is a member of several psychiatric associations and public-sector mental health and non-profit boards of directors. She highlighted that the Massachusetts General Hospital Center for Law, Brain and Behavior publishes all of its research, briefs, instructional videos, and attorney toolkit on the CLBB NeuroLaw Library—a free, open-sourced research library. It includes modules on topics including substance-use disorders in the law, juvenile and emerging adult development, brain development, sentencing reform, and elder fraud and cognitive decline.
“This is why we do what we do,” Dr. Edersheim expressed. “We educate federal and state judges about how brain science can improve the legal system. We write amicus briefs, ‘friend-of-the-court briefs’ on critical issues of neuroscience. We produce scholarly white papers so that everyone else can have all the knowledge that we have translated into legal categories, and we work with local district attorneys to create alternatives to incarceration for emerging adults, 18 to 25.”
Dr. Edersheim’s lecture was part of the Weaver Program’s Distinguished Lecture series. The Weaver Family Program in Law, Brain Sciences, and Behavior is committed to funding research at the intersection of neuroscience and law to foster conversations about fundamental legal concepts and advances in neuroscience. The program honors leading clinical and forensic psychiatrist Glenn M. Weaver, his wife Mary Ellen Weaver, and the Weaver family.
Watch the lecture below or on our YouTube Channel.