It has become increasingly common for brain images to be proffered as evidence in criminal and civil litigation. This Article - the collaborative product of scholars in law and neuroscience - provides three things.

First, it provides the first introduction, specifically for legal thinkers, to brain imaging. It describes in accessible ways the new techniques and methods that the legal system increasingly encounters.

Second, it provides a tutorial on how to read and understand a brain-imaging study. It does this by providing an annotated walk-through of the recently-published work (by three of the authors - Buckholtz, Jones, and Marois) that discovered the brain activity underlying a person's decisions: a) whether to punish someone; and b) how much to punish. The annotation uses the 'Comment' feature of the Word software to supply contextual and step-by-step commentary on what unfamiliar terms mean, how and why brain imaging experiments are designed as they are, and how to interpret the results.

Third, the Article offers some general guidelines about how to avoid misunderstanding brain images in legal contexts and how to identify when others are misusing brain images. The Article is a product of the 'Law and Neuroscience Project', supported by the MacArthur Foundation.