Abstract: The United Nations Convention on the Rights of Persons with Disabilities requires states parties to ‘recognize that persons with disabilities enjoy legal capacity on an equal basis with others in all aspects of life.’ This mandate has sparked debate about the interpretation of legal capacity, including within the criminal context as applied to the retrogressively named ‘insanity defense.’ Yet, under-examined are two questions: First, what defenses should defendants with psychosocial disabilities be able to invoke during criminal prosecutions? Second, what kind of evidence is consistent with, on the one hand, determining a defendant’s decision-making capacity to establish culpability and, on the other hand, the right to equal recognition before the law? Developments in neuroscience offer a unique prism to grapple with these issues. We argue that neuroscientific evidence of impaired decision-making, insofar as it presents valid and interpretable diagnostic information, can be a useful tool for influencing judicial decision-making and outcomes in criminal court. In doing so, we oppose the argument espoused by significant members of the global disability rights community that bioscientific evidence of psychosocial disability should be inadmissible to negate criminal responsibility. Such a position risks more defendants being punished harshly, sentenced to death, and placed in solitary confinement.