There are some distinct methodological challenges, and possible pitfalls, for neuroethics when it evaluates neuroscientific results and links them to issues such as moral or legal responsibility. Some problems emerge in determining the requirements for responsibility. We will show how philosophical proposals in this area need to interact with legal doctrine and practice. Problems can occur when inferring normative implications from neuroscientific results. Other problems arise when it is not recognized that data about brain anatomy or physiology are relevant to the ascription of responsibility only when they are significantly correlated with the psychological capacities contemplated by the legal formulations of responsibility. We will demonstrate this by considering two significant cases concerning psychopathy. Some paradigms that aim at measuring higher-order capacities, such as moral understanding, have limited validity. More robust paradigms for the study of learning in restricted controlled conditions, on the other hand, have limited ecological validity across individuals and context to be of any use for the law.