The October 1999 Term was a year of consolidation in the law of police investigations in constitutional criminal procedure. In four short and compact opinions--three supported by sizeable majorities and three written by the Chief Justice--the Supreme Court synthesized and consolidated its criminal procedure jurisprudence, and offered clear guidance to law enforcement officers and private citizens alike. Miranda warnings are required by the Fifth Amendment, and the police must continue to "Mirandize" citizens before conducting any custodial interrogations.(1) Reasonable suspicion under the Fourth Amendment calls for a totality-of-the-circumstances test, and a citizen's flight from the police in a high crime neighborhood amounts to reasonable suspicion sufficient to justify a Terry stop and frisk.(2) In contrast, a tip from an anonymous informant merely describing a suspect does not give rise to reasonable suspicion.(3) The reasonable expectation of privacy test continues to govern whether the Fourth Amendment protections are triggered, and travelers have a reasonable expectation of privacy in opaque soft-sided luggage.(4)
We have differences of opinion as to the outcome in some of these cases. And we have sharply disagreed in the past about the soundness of other criminal procedure decisions. Last Term, for instance, we parted company on the desirability and constitutionality of Chicago's anti-gang loitering ordinance. In the Morales litigation, one of us, Tracey Meares, co-authored an amicus brief in support of the ordinance and directed the Supreme Court's attention to empirical evidence of its effectiveness in combating gang-related violence in Chicago.(5) Bernard Harcourt took issue with Meares on both the wisdom and the validity of the Chicago ordinance and challenged the empirical foundation for one of the principal theories behind the ordinance, namely the broken windows theory.(6) Still today, we disagree strongly about what the empirical evidence proves, how to approach the empirical issues, and how properly to balance the interests at stake.(7)
In this Foreword, however, we put aside our differences and link arms to call for a new generation of criminal procedure jurisprudence, one that places empirical and social scientific evidence at the very heart of constitutional adjudication. We are calling for a mode of judicial decision-making and academic debate that treats social scientific and empirical assessment as a crucial element in constitutional decision-making, thereby making criminal procedure decisions more transparent. By more transparent, we mean to describe adjudication that expressly and openly discusses the normative judgments at the core of constitutional criminal procedure. Judicial decisions that address the relevant social science and empirical data are more transparent in that they expressly articulate the grounds for factual assertions and, as a result, more clearly reflect the interpretive choices involved in criminal procedure decision-making. We are not so naive or idealistic as to think that increased attention to empirical evidence will guarantee right answers in criminal procedure cases. But use of empirical evidence will produce a clearer picture of the existing constitutional landscape and spotlight the normative judgments at the heart of criminal procedure cases.
In this sense, we are calling for a third path in the larger constitutional debate between Richard Posner's empiricism and Ronald Dworkin's interpretivism. We agree with Posner that "the lack of an empirical footing ... always has been the Achilles heel of constitutional law, not the lack of a good constitutional theory,"(8) but we are not writing against constitutional theory. To the contrary, we endorse the Court's balancing-of-interests jurisprudence in the criminal procedure context and suggest that it in fact invites consideration of empirical evidence in the normative task of weighing competing constitutional interests. We emphasize, however, that the need for increased attention to social science data is equally important under more formalist or rights-oriented jurisprudential approaches. We agree with Dworkin that interpretive judgments are central to constitutional decision-making, but we disagree with his claim that these judgments can be made in an empirical vacuum.(9) Theoretical principles cannot properly resolve difficult criminal procedure cases without the assistance of empirical evidence. The most current and reliable empirical and social scientific evidence must inform the normative judgments at the heart of constitutional criminal procedure.
Indeed, greater attention to empirical and social science evidence is necessary precisely in order to shed better light on the normative judgments that we make in criminal procedure. We are writing this Foreword together to emphasize that the turn toward empirical and social scientific research is neither ideologically motivated, nor outcome determinative. In the words of another commentator, "Facts cannot replace constitutional theory, nor can they mechanistically resolve questions posed by theory. Instead, empirical knowledge is most useful in unmasking the theoretical assumptions that undergird constitutional law, in focusing those theories, and in contributing to a multidimensional view of society that informs the substance of constitutional law."(10)
THE LANDSCAPE OF MODERN CRIMINAL PROCEDURE
Modern constitutional criminal procedure emerged in a legal culture shaped by American legal realism and historically has been driven by empirical and pragmatic concerns about police practices, police-civilian encounters, crime prevention and detection, and civil liberties. One of the most notable features of the constitutionalization of criminal procedure in the 1960s was the Supreme Court's focus on the realities of street policing, custodial interrogations, investigations, and the impact of these activities on individual freedoms. Judicial decisions and academic writing in modern criminal procedure, to a far greater extent than in most legal fields--especially other areas of constitutional law--routinely centered on empirical issues surrounding the effectiveness of police practices and their impact on liberty interests.
The Court's recognition and embrace of real world experience forced a rejection of the formalism characteristic of nineteenth century Fourth and Fifth Amendment decisions.(11) Modern criminal procedure jurisprudence gravitated naturally toward a balancing-of-interests approach. As a result, it is commonplace today to describe constitutional rights relating to criminal procedure as guaranteeing a reasonable balance between liberty and order.(12) While recognition of this kind of balancing is thought to be the hallmark of interpreting the guarantees of the Fourth Amendment,(13) it is also relevant to analysis of the Fifth and Sixth Amendments as well.(14) It reflects, in effect, a larger form of constitutional reasoning that has become, as Alexander Aleinikoff remarked in a 1987 article, "widespread, if not dominant, over the last four decades."(15)
We refer to this balancing of liberty and order interests as a "balancing-of-interests" jurisprudential approach. It is different than the conventional balancing test used in cases like Mathews v. Eldridge, which weighs costs and benefits in a particular case. It calls, instead, for balancing liberty and order interests at a higher level--at the level of formulating criminal procedure rules, like the requirement of "reasonable suspicion" rather than "probable cause" in the stop-and-frisk encounter, or the extension of the concept of "legal compulsion" to the police station house under the Fifth Amendment.
The Court's tendency to engage in this kind of balancing in the constitutional criminal procedure context is pervasive. So pervasive, in fact, that it is often taken for granted. Consider the case of Schneckloth v. Bustamonte.(16) This case is best known for establishing a fact-intensive totality-of-the-circumstances review where a suspect has consented to a police search. In Schneckloth, the Court refused to require that the consenting individual have knowledge of her right to refuse the search as a prerequisite to establishing voluntariness.(17) Instead, the Court adopted a totality-of-the-circumstances test to assess whether the person searched consented to the police action.(18) While the totality-of-the-circumstances test is not itself a balancing analysis,(19) notice how the Court defined the voluntariness test in Schneckloth:
As with police questioning, two competing concerns must be accommodated in determining the meaning of a "voluntary" consent--the legitimate need for such searches and the equally important requirement of assuring the absence of coercion.(20) In other words, the Court treated "voluntariness" itself as a balancing of the needs of efficient law enforcement and protection against coercion--of order and liberty. The assessment of "voluntariness" is by no means simply an assessment of the consenting party's state of mind at the time of the search and consent.(21) Nor is "voluntariness" merely a question of the propriety of police conduct, such as the failure to apprise an individual of her right to refuse the search.(22) Instead, the Court made "voluntariness" a placeholder for an analysis of the competing interests of order and liberty--for a balancing-of-interests approach. In effect, it is the resulting balancing that determines the scope of the right.(23)
The gradual and relatively recent emergence of modern criminal procedure--and with it, of the balancing-of-interests approach in constitutional criminal procedure--has been a mixed blessing. On the one hand, the adoption of balancing tests may promote a potentially more transparent mode of judicial decision-making in criminal procedure. Explicit balancing may encourage the judiciary to be more honest about the...