Pain as Fact and Heuristic: How Pain Neuroimaging Illuminates Moral Dimensions of Law

Important legal distinctions turn on the presence and degree of physical pain. Statutes refer to degrees of physical pain to define criminal offenses like torture-murder,1 while pain that rises to the level of cruelty draws the boundary between constitutionally permissible and impermissible punishment.2 Claims about pain motivate legislative action to protect previously unrecognized classes, such as in several states’ recent passage of statutes concerning fetal pain and fetal anesthesia during abortion.3 In legal domains ranging from tort to torture, pain and its degree do important definitional work by establishing boundaries of lawfulness and of entitlements. For all of the work done by pain as a term in statutes, treatises, constitutions, and administrative- and common-law jurisprudence, it has had a troubling lack of externally verifiable reality.4 Like other subjective, affective states, pain has been invisible and, frequently, unspeakable.5 Though we have been able to impute pain based on experience or knowledge or by observing expressions of it in behavior, we have not been able to observe or measure it directly.6 For this reason, claims of great pain come with great doubt.