Criminal innovation and the warrant requirement: reconsidering the rights-police efficiency trade-off.

• Author: Jacobi, Tonja
• Position: Abstract through II. Criminal Innovation, p. 759-791

ABSTRACT

It is routinely assumed that there is a trade-off between police efficiency and the warrant requirement. But existing analysis ignores the interaction between law-enforcement investigative practices and criminal innovation. Narrowing the definition of a search or otherwise limiting the requirement for a warrant gives criminals greater incentive to innovate to avoid detection. With limited resources to develop countermeasures, law enforcement officers will often be just as effective at capturing criminals when facing higher Fourth Amendment hurdles. We provide a game-theoretic model that shows that when law-enforcement investigation and criminal innovation are considered in a dynamic context, the police efficiency rationale for lowering Fourth Amendment rights is often inapt. We analyze how this impacts both criminal activity and innocent communications that individuals seek to keep private in the digital age. We show that both law-enforcement and noncriminal privacy concerns may be better promoted by maintaining the warrant requirement.

INTRODUCTION I. THE ROLE OF THE FOURTH AMENDMENT IN LAW-ENFORCEMENT INVESTIGATIONS A. The Warrant Requirement and the Manipulation of Definitions of a Search B. The Distorting Effect of the Assumption that Warrants Impede Investigations II. CRIMINAL INNOVATION A. Existing Scholarship on Criminal Innovation B. Criminal Innovation and the Police Efficiency Assumption III. AN ECONOMIC MODEL OF CRIMINAL INNOVATION AND THE WARRANT REQUIREMENT A. Criminal Utility B. Law-Enforcement Activity C. Game-Theoretic Solutions D. When Is the Assumption Violated? IV. DISCUSSION AND POLICY IMPLICATIONS A. General Implications B. Application to Private Communication in the Digital Age 1. E-mail and Encryption 2. Data Destruction Programs 3. Switching Costs and the New Context: Mass NSA Searches CONCLUSION INTRODUCTION

"Little" Melvin Williams was an infamous heroin and cocaine trafficking kingpin in Baltimore in the 1970s and early 1980s. (1) When the police began investigating Williams's operation, they discovered that his gang had taken many ingenious measures to avoid police detection. (2) One such innovation was the invention of a secret code for pager communications between members of the gang. (3) Why create a special code? Because U.S. Supreme Court doctrine allows police, without a warrant, to monitor telephone numbers dialed on the public payphones the gang used to send messages to pagers. The content of the messages was the telephone number that the recipient was supposed to call. (4) The gang invented a way to mask the messages that were sent to the pagers--each number was replaced by the number opposite the "5" on the keypad, and "5" was replaced with "0." (5)

It made sense to invent a code for pager messages and to teach the code to its members because the gang knew the police could otherwise identify the pager numbers without the cost and evidentiary burden of acquiring a warrant. (6) Law enforcement officers (LEOs) (7) are more likely to use investigative techniques like tracking telephone calls when they can avoid the costs of obtaining a warrant. When LEOs are not bound by the warrant requirement, the expected benefits of an investigation (the possibility of finding evidence) are more likely to outweigh its costs (the time and effort expended by investigation). But when faced with a higher likelihood that law enforcement will investigate their crimes, criminals have a greater incentive to try to cover up each crime: in other words, to innovate. That criminal innovation, inspired by law enforcement's ability to investigate without a warrant, may slow down an investigation as much as the warrant requirement. The Williams gang's innovation made the LEO investigation much more difficult because the police had to create "clone" pagers, which shared the same telephone numbers as the gang members' pagers. (8) The police were eventually able to crack the code, but the innovation significantly delayed the police investigation, and could easily have derailed it entirely. (9)

Today, instead of pager codes, criminal conspiracies commonly use prepaid cell phones for communication (10) because those devices are harder for LEOs to trace or to tie to specific people. (11) Prepaid phones are inexpensive, allowing criminals to dispose of them frequently to avoid being linked to the calls made. (12) They are also more difficult to trace because purchasers can provide false names and addresses to phone providers. (13) But inventing pager codes and purchasing prepaid cell phones are only two of the many actions criminals can take to avoid being identified. Even casual observers of detective stories and crime capers will be familiar with many other mechanisms of classic crime detection avoidance. Bank robbers use masks to prevent identification by witnesses, burglars use gloves to hide their fingerprints, and gunmen use silencers so that their crimes do not attract attention. (14)

In the digital age, many forms of sophisticated detection avoidance have been developed, from simple steps such as anonymous e-mail accounts, to complex encryption of computer programs to mask the content of computer files and Internet activity, to convoluted rerouting of internet traffic to avoid location identification. For example, the reopened "Silk Road" Internet marketplace, which serves as an online black market, primarily for illegal drugs, (15) has multiple mechanisms to avoid law-enforcement investigations. Users are required to install the Tor network, a software system that facilitates anonymity by rerouting IP addresses behind firewalls and using multiple layers of encryption. (16) Only the unregulated electronic currency "Bitcoin" is accepted, (17) and sellers are required to delete all unique buyer information after confirmation of an item's arrival. (18) All of these mechanisms provide additional assurances of anonymity.

Clearly, criminal innovations can take many forms, including new business methods as well as traditional masking techniques. Innovations are costly in time and effort but are undertaken because they reduce the likelihood that criminal participants will be caught. The possibility of warrantless investigations intensifies these behaviors. For example, some of the Silk Road innovations are designed specifically to avoid warrantless law-enforcement investigations. LEOs need only a subpoena--not a warrant backed by probable cause--to install the computer equivalent of a pen register, which allows them to track "the to/from address of [a suspect's] email messages, the IP addresses of the websites that [a suspect] visited and the total volume of information sent to or from [a suspect's Internet] account." (19) The National Security Agency (NSA) can, without a warrant, analyze identifying information, such as IP addresses, in communications between Americans and foreigners and can search its massive databases of communications data--some of it solely domestic--for the identifying information of specific individuals. (20) The Silk Hoad's built-in protections from such warrantless investigatory powers make the job of investigators much more difficult--perhaps as difficult as it would be if the warrant requirement were applied to tracking IP addresses. (21)

Local police and federal agents often undertake large-scale, sometimes multiyear, multiagency investigations that involve a back-and-forth between criminal innovation and law-enforcement counterresponse. This is illustrated by the international tracking and capture of Joaquin Guzman Loera, also known as "El Chapo," chief of the world's biggest drug-trafficking cartel, Sinaloa in Mexico, who was involved in a combination of high-tech and low-tech criminal innovation. (22) Guzman evaded the Drug Enforcement Administration (DEA), Mexican intelligence, and special forces, among other agencies, for eight years by using both sophisticated encryption programs and simple avoidance of direct phone conversations, combined with a complicated system of intermediaries and relays:

If you needed to communicate with the boss, you could reach him via B.B.M., BlackBerry's instant-messaging application Your message would go not directly to Guzman, however, but to a trusted lieutenant, who spent his days in Starbucks coffee shops and other locations with public wireless networks. Upon receiving the message, the lieutenant would transcribe it onto an iPad, so that he could forward the text using WiFi--avoiding the cellular networks that the cartel knew the authorities were trolling. The transcribed message would be sent not to Guzman but to a second intermediary, who, also using a tablet and public WiFi, would transcribe the words onto his BlackBerry and relay them to Guzman. Although Guzman continued to use a BlackBerry, it was almost impossible to track, because it communicated with only one other device. (23) This "mirror" system was almost impossible for the authorities to penetrate, but by studying the patterns of the cartel's communications, the DEA was able to locate Guzman's intermediaries, and eventually physically locate him at the home of a coconspirator. (24)

From balaclavas to computer encryption, all of these criminal behaviors decrease, to a greater or lesser extent, the probability that LEOs will find evidence linking an individual to a crime. In this Article, we consider all such measures under the general concept of "criminal innovation." These are actions that take place prior to a criminal's arrest to avoid identification, as opposed to actions taken following an arrest to avoid conviction, such as influencing witnesses or consulting experts. (25)

Most forms of criminal innovation are uninteresting to analyze because due to their low cost and large benefit, criminals will have a clear incentive to make use of them, and law enforcement can do little to counteract their effectiveness. For a criminal robbing a bank, wearing a...