Pain detection and the privacy of subjective experience.

I. INTRODUCTION A neurologist with abdominal pain goes to see a gastroenterologist for treatment. The gastroenterologist asks the neurologist where it hurts. The neurologist replies, "In my head, of course."1 Indeed, while we can feel pain throughout much of our bodies, pain signals undergo most of their processing in the brain. Using neuroimaging techniques like functional magnetic resonance imaging ("fMRI") and positron emission tomography ("PET"), researchers have more precisely identified brain regions that enable us to experience physical pain.2 Certain regions of the brain's cortex, for example, increase in activation when subjects are exposed to painful stimuli.3 Furthermore, the amount of activation increases with the intensity of the painful stimulus.4 These findings suggest that we may be able to gain insight into the amount of pain a particular person is experiencing by non-invasively imaging his brain. Such insight could be particularly valuable in the courtroom where we often have no definitive medical evidence to prove or disprove claims about the existence and extent of pain symptoms. In fact, pain is one of the easiest medical complaints to feign.5 Yet, given that pain and suffering awards may represent about half of personal injury damage awards,6 if even a small percentage of those awards involve feigned or grossly exaggerated symptoms, billions of dollars may be redistributed each year to malingering plaintiffs. On the other hand, if litigants raise genuine claims that we fail to recognize, billions of dollars may fail to reach those who properly deserve compensation for injuries.7 In this symposium article, I will argue that, despite many conceptual and technological challenges, neuroimaging may someday play a critical role in the evaluation of pain claims. In recent years, a burgeoning literature has developed on how neuroimaging may inform our understanding of deception,8 moral and legal responsibility,9 behavior prediction,10 and much more." There has been very little analysis, however, of the societal implications of neuroimaging technologies that provide insight into our subjective experiences,12 even though researchers have used neuroimaging to observe our brains while we experience not only pain but also happiness, sadness, anger, fear, and disgust.13 While we are still a long way from understanding these complicated phenomena, neuroimaging has been and will continue to be at the forefront of neuroscience research into the nature of subjective experience. It may well be time to consider some of the legal and ethical issues that such technology may raise.14 Subjective experiences such as pain are private in two quite different senses. First, they are private in the descriptive sense. No one else knows exactly what I am feeling at a particular moment, and no one else can directly experience my feelings. While I can infer that others are in pain, I have uniquely direct access to my own pain. "One does not say that one is in pain on the grounds that one is groaning and assuaging one's injured limb."15 Rather, "it is because I can introspect that I can say how things are with me without observing what I do and say."16 Second, subjective experiences are private in the normative sense. In some cases, we ought not be forced to reveal information about what we are feeling. For example, one might reasonably believe that we have some interests in keeping private when we are in pain, how much pain we are in, what triggers our pain, and how sensitive we are to pain. Such privacy interests may partially explain why we legally restrict disclosure of medical records. Similarly, we may have interests in keeping private other subjective experiences like embarrassment and sexual arousal. Even though we sometimes betray our own emotions involuntarily through comments, gesticulation, and facial expressions, in some cases, we may plausibly have rights to be free from certain unwanted inquiries into our subjective experiences. …