Savvy criminals constantly develop new techniques to target U.S. persons, businesses, and interests. Central to the evolution of modern-day crime are four broad operational realities—geographic borders, criminal turf, cyberspace, and law enforcement jurisdiction. Individual criminals as well as broad criminal networks exploit these realities and often leverage the unique characteristics of one against the other to dodge law enforcement countermeasures and efforts to disrupt illicit activity. Further, the interplay of these realities can potentially encumber policing measures. In light of these interwoven realities, policy makers may question how to best design policies to help law enforcement combat ever-evolving criminal threats. In the first operational reality, criminals routinely take advantage of geographic lines. They thrive on their ability to illicitly cross borders and provide illegal products or services. Indeed, much criminal activity is predicated on the ability to subvert border security regimens, thus earning a premium from black market clients and customers. Drug trafficking organizations (DTOs), for example, have constructed increasingly sophisticated cross-border tunnels to smuggle illegal drugs from Mexico into the United States. And, smugglers and fraudsters ship counterfeit goods from overseas, flooding U.S. markets with sham goods and depriving genuine manufacturers of profits. The second reality is broadly related to the first. Some larger criminal groups even establish their own operational "borders" by defining and defending the "turf" or territories they control. These boundaries are not formally recognized by law enforcement authorities, but they have strong influence in the criminal underworld. In fact, much of the violence in Mexico along the U.S. Southwest border revolves around rival DTOs clashing over territorial control. The outlines of turf can cross borders at the national, state, and local levels, thus complicating policing efforts. The third reality involves a largely borderless, virtual environment where criminals carry out illicit business. Criminals operate in the cyber world partly to circumvent more conventional, established constructs such as international borders. In the virtual realm, criminals can rely on relative anonymity and a rather seamless environment to conduct business. For instance, some criminals use electronic banking systems to quickly smuggle cash out of one nation and into another. Finally, U.S. law enforcement often remains constrained by geographic and legal boundaries or even its own notions of "turf"—partly defined in terms of competing agency-level priorities and jurisdictions. U.S. officials have suggested that as criminals have evolved their operations, they have relied less on turf to conduct business; the same evolution is unclear regarding U.S. law enforcement. Law enforcement agencies, even while collaborating through means such as interagency agreements, task forces, and fusion centers, retain investigational jurisdiction over certain categories of crime. And recent reports have suggested that interagency disagreements over organizational boundaries may remain. In addition to challenges presented by each of these four operational realities individually, law enforcement faces hurdles presented by the overlap of any or all of the realities. Complicating this, policy changes in one reality—both administratively and legislatively—can impact criminal activity and law enforcement countermeasures in other realities. Policy makers have expressed interest in ensuring that law enforcement is keeping pace with 21 st century criminals who threaten American society. Given that criminal investigations unfold in an environment of geographic borders, criminal turf, borderless cyberspace, and law enforcement jurisdictions, policy makers may question how to direct policy to best enable U.S. law enforcement to target contemporary criminals. For instance, Congress may choose to examine whether law enforcement agencies are effectively coordinating their investigations through the use of interagency agreements, task forces, and fusion centers. Policy makers may also debate whether law enforcement has the existing legal authorities, technology, and resources—both financial and manpower—to counter 21 st century criminals. One of the principal debates for policy makers may be whether, or how, to design policies that cut across multiple operational realities. This report examines the four operational realities within which law enforcement and crime operate. It analyzes the challenges for U.S. law enforcement in each of these realities individually and in selected cases where they overlap. The report also discusses how law enforcement has adapted to combat present-day criminals. Throughout, it raises questions regarding how Congress may leverage its legislative and oversight roles to help U.S. law enforcement most effectively protect U.S. persons, businesses, and interests. Physical and virtual boundaries play significant roles in both criminal activity and police work. In the physical world, recognized borders delineate the lines of municipal, state, and national authority. At their most basic level, legally defined geographic borders outline the sovereignty of these entities. For example, at official crossings along the U.S. border with Mexico, law enforcement presence helps to distinguish one nation from another. Between ports of entry, the U.S. Customs and Border Protection (CBP) has deployed personnel, technology, and tactical infrastructure along the Southwest border to impede the illegal entry of vehicles and unauthorized persons. When it comes to criminal turf, the virtual realm, and law enforcement jurisdictions, the lines separating one authority—legitimate or illegitimate—from another often grow fuzzier. The following sections lay out discussions of borders, turf, cyberspace (the virtual world), and jurisdiction that help shape modern criminal activity as well as law enforcement counter efforts. As suggested, physical or geographic borders—whether they divide countries, states, or even neighbors' plots of land—are often recognized with relative ease. Frequently, there are signals indicating when one is entering or leaving a given geographic area. Road signs, for instance, may provide notice of crossing from one city, county, state, etc., to another. International border checkpoints can signal that one is entering or leaving a country. Along several portions of the Southwest border, a fence separates the United States from Mexico. Such physical boundaries may aid in delineating the space within which a given set of rules applies. Nations have sovereign control over their countries and territories and may enforce the laws of their lands within those bounds. In the United States, the federal government is responsible for enforcing federal laws within the country, and each state is responsible for enforcing state laws within its physical borders. And, rules that hold in one state may not apply in a neighboring state with different laws. For example, stealing $500 worth of goods is considered felony theft in New Mexico, but a criminal needs to steal $1,000 worth of goods in neighboring Arizona for the crime to reach the felony theft threshold. Similarly, laws that apply in certain states may not apply under federal law to the country as a whole. Globalization, technological innovation, and heightened security concerns have complicated traditional understanding of borders. Business, for instance, has become increasingly borderless; so, too, have criminal enterprises. Since the terrorist attacks of September 11, 2001, the United States has experienced an expanded tension between border protection concerns and free market ideals. Open border regimens are encouraged by a desire for efficiently moving goods and services. However, security screenings and concerns over safety may slow down the transit of these items. Criminals may then capitalize on any weaknesses in border regimens to supply black market goods and services where there is a demand. In other words, border protection systems and enforcement efforts can have the unintended consequence of introducing inefficiencies to market systems. These inefficiencies can, in turn, present profitable opportunities for criminal networks. Some criminals—such as drug cartels and street gangs—have established turf boundaries for their operations. These boundaries may or may not coincide with geographically and legally defined borders. Criminal turf often delineates a territory within which illegal entities carry out their operations. In the United States, street gang warfare has historically centered around the establishment and protection of turf. Other criminal networks have used various means to establish operational turf as well. For instance, in February 2011, 22 members of a violent, fraudulent document-trafficking organization (including the manager of the organization's U.S. operations) were indicted for crimes including the use of "brutal violence to eliminate rivals, protect its turf and enforce discipline against its own members." The organization, based in Mexico, has operations in 19 U.S. cities and 11 states, selling counterfeit Resident Alien and Social Security cards to unauthorized immigrants. The suspects in this case allegedly protected the organization's turf by posing as customers looking to buy the counterfeit identification cards. The "customers" would then attack competitors when they met for a supposed sale. Victims' hands, feet, and mouths were bound, and they were beaten and threatened with death should they continue to operate on the organization's turf. Turf may be readily established in the real world, as criminals can rely upon the physical environment to establish territory. In the cyber world, however, it may appear to be difficult to establish virtual turf lines, but they exist nonetheless. For example, two Trojans, believed to be based in Russia, engaged in a cyber turf battle in 2010. The two Trojans—ZeuS and its smaller competitor, SpyEye—would both steal online banking information. They would then transfer funds to money mules, or U.S. residents with bank accounts, who would then move the money out of the United States. SpyEye challenged ZeuS by stealing information from ZeuS and then removing the ZeuS toolkit from infected computers. The turf war reportedly ended when the ZeuS Trojan was no longer maintained and its code was allegedly merged with that of SpyEye. As mentioned, the relatively clear borders and turf lines within the physical world are not replicated in the virtual realm. Of course, some distinct boundaries separate the physical and the cyber worlds; a keyboard, mouse, screen, and password can all mediate between these physical and virtual realms. Within cyberspace, however, the notion of a border is much more nebulous.