In the contemporary debate on the use of the neurosciences in ethics and law, numerous arguments have been bandied about among scientists and philosophers looking to uphold or reject the reliability and validity of scientific findings obtained by brain imaging technologies. Among the most vexing questions is, Can we trust that technology? One point of disagreement is whether brain scans offer a window through which to observe the functioning of the mind, in such a way as to enable lawyers, judges, physicians, and lawmakers to detect anomalies in brain function that may account for criminal unconscious behavior. Those who stand behind brain imaging believe that this can indeed be achieved, whereas those in opposition stress that brain scans are highly open to interpretation and that the data they provide is insufficient to establish causal connections. The question essentially comes down to whether technology can reliably be used to determine the intentions of the individual, thus establishing mens rea, for example, and hence responsibility. This article focuses on the latter notion and explores whether we can rely on the neurosciences to shed light on a complex form of moral and legal reasoning, as well as the role of the neurosciences in reawakening a philosophical and legal interest in trying to set responsibility on an empirical basis.