American Journal of Law & Medicine

A brave new world of interrogation jurisprudence?(Brain Imaging and the Law)

I doubt that the uneasiness about electrical lie detectors would disappear even if they were refined to place their accuracy beyond question. Indeed, I would not be surprised if such a development would only heighten the sense of unease and the search for plausible legal objections. (1)


We are told that functional magnetic resonance imaging (fMRI) is "not ready for use, despite optimism about its commercial potential." (2) This is probably true--it is also, in terms of legal analysis, irrelevant. Although the development of fMRI technology is still in its relative infancy, there is no guarantee that the law governing its use will wait for it to grow up. Thus, the recent backlash against the initial flurry of articles, both academic and general, on the promise and legal issues surrounding fMRI is unwarranted. The conclusion that so many--even many of the contributors to this volume--seem to be drawing, namely, that law, as a field, must abstain from analyzing the legal implications of fMRI until those with more scientific expertise deem it ready to look at, is at best wrong and, at worst, irresponsible.

The emerging conventional wisdom of disengagement is misguided for two reasons. First, it is based on a naive view of the common law process in general and stare decisis in particular. Historically, fundamental decisions regarding the implications of new technologies have occurred very early in the life cycles of those technologies. (3) For example, polygraphs have been in legal disrepute since 1923. (4) This trend dates to the oft-cited, remarkably brief, almost universally misinterpreted Frye v. United States, (5) which has been erroneously read to establish a per se rule against the admissibility of evidence obtained with a conventional lie detector. (6) Similarly, the leading Supreme Court authority addressing confessions obtained with truth serum was decided over forty years ago, in the relative infancy of psycho-pharmaceuticals. (7) These technologies have evolved considerably since the courts originally addressed them, (8) however, the mere existence of these opinions have tended to foreclose fresh analyses, usually resulting in nothing more than their uncritical invocation rather than a reasoned examination of the law and policy issues. (9)

The converse is also true. Reliance on fingerprints (10) and eyewitness identifications (11) are firmly embedded in the legal system, although, empirically, a strong case could be made that neither is all that reliable. As much as we would like not to admit it, once a legal system determines a particular technology to be dubious (such as polygraphs) or helpful (such as fingerprint analysis), such characterization is immensely difficult to unseat. (12) There is no reason to suspect this process will be different with fMRI, and, in fact, every reason to believe it will be the same. Thus, there is great value in getting things right from the beginning, the very beginning.

Second, the disengagement view ignores the fact that the legally salient elements of fMRI are not subject to scientific disagreement. Said simply, the scientific dispute is not with respect to how fMRI itself functions, and how such functioning could compromise an individual's privacy, but, rather, as to how effective the technology is at doing it. (13) We should not have abstained from considering the potential legal implications of DNA testing until more reliable polymerase chain reaction testing replaced restriction fragment length polymorphism, (14) and we should not abstain here. Yet to be resolved details of the scientific analysis will surely inform elements of the legal one; however, in the main, it is, as will be shown below, entirely possible to discuss the potential privacy implications of the device at present.

The ultimate scientific conclusion may well be that fMRI is, as a technology, untenable for the purposes at issue here, in which case all the ink we will have spilled on the topic will have been for naught--admittedly a problem virtually unheard-of in the always-timely, real-world-relevant world of contemporary legal scholarship. (15) On the other hand, if the existing scientific literature is indeed a harbinger of an important new technology, it will be to society's benefit that some thought have been put into its implications before its wide scale deployment.

Moreover, to the extent that we as a society have objections to a technology that at least possesses the potential for serious invasiveness, we ought not to couch such objections merely in terms of technological inadequacy. Yes, there may be problems with using an fMRI device in the interrogation context and, obviously, if such a device proves not to be reliable, it should not be used. (16) But limiting ourselves to the technological elements implies that should the technology prove feasible, there would be no other objections. Of course, as with lie detectors, it may be the case that even in the face of significant advances in the state of the art, courts will continue to regard the technology with too much suspicion to permit its use. In an age of mass casualty terrorism, however, there is serious reason to question whether such concerns will continue to preclude the use of a device that could have intelligence value.

Thus, even though there are impediments to the wide-scale use of fMRI at present, we must begin to examine these complex issues now. As such, in this Article, I attempt an initial analysis of the likely treatment of fMRI under American domestic law and, more broadly, the implications for the way in which we treat it. I focus on the Constitutional issues potentially implicated by the technology, particularly issues related to the Fifth Amendment's Self Incrimination Clause (17) and the Due Process Clause. (18) I argue existing jurisprudence in this area is conceptually incapable of addressing fMRI, which requires that we engage in a much more searching and fundamental analysis about implications physical invasions have on mental privacy. Moreover, to the extent that incomplete scientific knowledge hinders this analysis, it is not the underdevelopment of fMRI that is the issue but the relationship between the physical brain and what humans regard (perhaps wrongly) as the non-physical manifestations of the self, whether this is called the mind, soul or conscious. Given, however, that neuroscience increasingly indicates that the traditional view of separation between brain and mind is erroneous, we should err on the side of caution and restrict the use of fMRI on the basis of its unique ability to compromise involuntarily an individual's mental privacy, rather than merely on the grounds of lack of reliability given the state of the art.


Superficially, the status of fMRI under the Self Incrimination Clause hinges on whether evidence gathered through it is more like spoken testimony against oneself or like DNA samples, fingerprints and blood tests. If like the former, then such evidence would not be admissible. If like the latter, such evidence would be. It is highly likely that fMRI's legal fate will be determined by how apt judges regard these respective analogies. Nevertheless, although this approach has intuitive appeal, it is wrong. Precedent in this area, and the artificial categories this precedent supports, is of little value, as fMRI challenges many of the fundamental presumptions made by judges in the common law tradition regarding the relationship between the physical brain and the mind. Attempts to force fMRI into these traditional categories, even if such forcing happens to give us our preferred result, whatever that may be, is both intellectually dishonest, potentially risky and ultimately unsatisfying.

Under the Self Incrimination Clause, a person may not be compelled "to be a witness against himself." (19) The purpose of this privilege is to prevent the accused from "having to reveal, directly or indirectly, his knowledge of facts relating him to the offense or from having to share his thoughts and beliefs with the Government." (20) A person is a "witness" against himself when he is "compelled to testify ... or otherwise provide the State with evidence of a testimonial or communicative nature." (21) The privilege does not, however, prevent the suspect from being "the source of 'real or physical evidence'." Thus, although it is settled that non-verbal conduct can fall within the scope of the privilege, (22) the privilege does not capture most physical tests, such as blood tests.

To be testimonial, the communication must "explicitly or implicitly . …

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