A thorough analysis of the question of whether we possess “free will” requires that we take into account the process of exercising that will: that is, the neural mechanisms of decision making. Much of what we know about these mechanisms indicates that decision making is greatly influenced by implicit processes that may not even reach consciousness. Moreover, there exist conditions, for example certain types of brain injury or drug addiction, in which an individual can be said to have a disorder of the will. Examples such as these demonstrate that the idea of freedom of will on which our legal system is based is not supported by the neuroscience of decision making. Using the criminal law as an example, we discuss how new discoveries in neuroscience can serve as a tool for reprioritizing our society's legal intuitions in a way that leads us to a more effective and humane system. Copyright © 2007 John Wiley & Sons, Ltd.