Science is once again claimed by some to provide probative evidence in our legal system, as it has so often in the past. Perhaps the closest contemporary analogy is the use of DNA analysis for identification of individuals. There, after many years, DNA evidence has become firmly established as reliable and relevant to many legal proceedings. Neuroimaging, however, is not so well established. The idea behind the technique is that cells in the brain that are in active use consume oxygen at an increased rate, and experience greater blood flow. The fMRI method effectively senses a change in the ratio of oxygenated hemoglobin to deoxygenated hemoglobin, which is taken to be a measure of cellular activity. The fMRI signals are eventually displayed as a two-dimensional representation, a cross-section of the brain, in which the active regions are lighted up. There are many open questions about interpretations of the images. One of the more obvious is: which regions of the brain, if any, are uniquely associated with pain sensation? Another has to do with how directly and rapidly the sensation of pain is expressed as increased cellular activity. Still a third is: can a person produce a convincing image of pain merely by conjuring up vivid thoughts of pain? These and other outstanding issues are being addressed on a continuing basis by highly active research programs throughout the world.
Definitive answers to many questions that have arisen in the use and interpretation of fMRI as a general measure of brain activity are lacking. That, however, has not impeded an avalanche of studies using the technique in hopes of finding answers to all sorts of questions in cognitive sciences and medicine. Many of these studies will eventually be advanced as potential evidence in legal proceedings. It will then be up to the judge, usually, to determine whether it should be admitted, using as guidelines the Federal Rules of Evidence and prior court cases. Among these the Daubert ruling of the Supreme Court has been highly influential. The Rules of Evidence and the Daubert ruling place a great deal of responsibility on the judge to understand enough of the science and methodology to determine whether the evidence will be conducive to finding the facts, or whether instead it could be misleading and prejudicial.
When the scientists working in a relatively new area such as fMRI are not in consensual agreement on the interpretations, reliability and details of best practice, science is unable to exercise an effective expert authority. If fMRI is pushed forward in its present state of development as reliable science it could easily come to be seen as pseudoscience, possessing a semblance of rigor that it in fact lacks. Science’s authority in society as a source of reliable knowledge of the natural world depends on many factors, among them the perception that science can attain truthful knowledge. The search for new knowledge, the evaluation of new results and the promulgation of those results within the science community is maintained by processes of internal control within the scientific community, such as peer review of submitted articles for publication, and various mechanisms for identifying the most significant new work. These processes work tolerably well, but they apply only indirectly to the communication of science to the larger society.
Scientists are like everyone else in wishing for recognition of their work by others; it should be no surprise that they sometimes bypass science’s normal review processes in promoting their work to non-scientists. We thus often see reports of studies that suggest new materials, medical treatments, tests and even potential cures when in fact the work is controversial, not fully corroborated or just plain slipshod. At times the science involved carries important public policy implications, touches on sensitive areas from an ethical perspective or may involve applications in the legal area, as with fMRI. Then the public notice it attracts, along with the evident conflicts within science regarding the meaning of the work or its significance, raises doubts in the public mind about science’s epistemic authority. For this reason, the scientific establishment has an interest in minimizing such public conflicts. One method for doing this is to have widely recognized panels of experts study the issues in controversial cases and issue reports of findings. The National Academies are regularly called upon to do this. They perform a unique public service by bringing together committees of experts in all areas of scientific and technological endeavor. These experts serve pro bono to address critical national issues and give advice to the federal government and the public. We can be sure that before long it will be necessary to convene a panel to assess the capacity of fMRI studies to reliably detect and measure the extent to which people experience pain. Until then, and perhaps even after such a report has issued, judges and juries will have to struggle with assimilating yet one more new body of scientific knowledge into our justice system.