Drug Interdiction

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The interdiction of illicit drugs into the United States is the effort to seize them, together with the transport and/or persons that carry them on their way from the producing country to the importing country; many of the Seizures occur just as the drugs are brought across the border. The principal drugs subject to U.S. interdiction are Cocaine and Marijuana, both of which are imported primarily from Latin America. The United States, uniquely among modern nations, has made interdiction a significant part of its effort to control the supply of drugs, at least for cocaine and marijuana, since about 1975. In addition to other federal agencies, it has involved the military in this effort. Though interdictors have seized large quantities of drugs, there are still numerous questions about the effectiveness of the program as a method of reducing the use of drugs, particularly cocaine.


Interdiction has two general goals. The primary one is to reduce the consumption of specific drugs within the nation by making it more expensive and risky for smugglers to conduct their business. Drug seizures raise costs by increasing the amount that has to be shipped in order to ensure that a given quantity will reach the market. Additionally, an effective interdiction program will, among other things, raise the probability that a courier is arrested, thereby increasing the price smugglers have to pay to those who undertake the task. These higher fees raise smugglers' costs of doing business and thus the price they must charge their customers, the importers. Finally, the increased costs lead to a higher retail price and serve to lower consumption of the drug.

At one time it was thought that interdiction could impose a physical limit on the quantity of drugs available in this country. With a fixed supply available in the producing nations, each kilogram seized on its way to the United States would be one less kilogram available for consumption here. However, this has not proven to be the case. It is now generally accepted that production is expandable and that increased seizures can be compensated for with increases in production, although farmers may have to receive higher prices to provide greater production.

A second, more modest, general goal is to increase the difficulty of smuggling itself and to provide suitable punishment. Smugglers, or at least the principals in smuggling organizations, are among the most highly rewarded participants in the drug trades. There is support for programs that conspicuously make their lives less easy and that subject them to the risks of punishment.

Three illegal drugs have traditionally dominated imports: cocaine, Heroin, and marijuana. Heroin is subject to only modest interdiction efforts because it is usually smuggled in conventional commercial cargo, or it is carried on (or within) the person of the smugglers who travel by commercial traffic; seizures are made only in the course of routine inspection of cargo and traffic. It is estimated that ten tons of heroin are smuggled into the United States each year, and seizures of more than ten kilograms are rare. The Drug Enforcement Administration (DEA) reported that a total of 667 kilograms of heroin had been seized in 1999, about the same amount seized in 1990. Cocaine and marijuana have been the primary targets of interdiction, although an effective program of interdiction against Colombian maritime smuggling has led to a sharp rise in the share of the U.S. marijuana market served by domestic producers.


The techniques of interdiction inevitably mirror those of smugglers. Drugs enter the United States by air, land, and sea, by private vessel and commercial carrier. Interdiction must, if it is to have any substantial effect on the drug trade, act against all the modes of smuggling; otherwise smugglers will rely on the mode that is not subject to interdiction.

Interdiction has three separate elements: monitoring, detection and sorting, and pursuit and apprehension. For example, U.S. Coast Guard ships supported by an extensive radar system patrol the Caribbean, which constitutes the major thoroughfare for smuggling from Latin America. The Coast Guard patrol vessels attempt to see, either directly or through radar, all ships moving along certain routes. This constitutes the monitoring activity. The interdictors must then sort, from all that traffic, the relatively small number that are carrying illegal drugs. Finally, they must pursue the smugglers that have been detected, arrest the personnel, and seize the drugs and the ship itself. The interdiction system is as weak as its weakest component; for example, a system that has good pursuit capacities but is unable to sort smugglers from innocents effectively will waste much of that pursuit capacity in chasing nonsmugglers. Similarly, good detection will lead to few captures without effective monitoring capabilities.

The Coast Guard and Customs Service share primary responsibility for marine and air interdiction. The Coast Guard patrols more distant routes, with Customs having a greater role in the U.S. coastal zone. Both agencies also conduct interdiction against private planes, with Customs having primary responsibility over the Mexican land border, a major trafficking area. The DEA expanded its air surveillance, having a fleet of ninety-five aircraft in 2000. The Border Patrol, a unit of the Immigration and Naturalization Service, has primary responsibility for the interdiction of drugs carried in cars or on persons crossing the land border. In the late 1990s, new technology, such as x-ray machines that examine commercial vehicles, was installed at border stations in the Southwest.

Both Customs and the Border Patrol make many seizures and arrests in the course of routine inspection. For example, Customs may find a shipment of cocaine concealed inside a cargo container being unloaded in the Miami port; the Border Patrol, in the course of pursing illegal immigrants, might find a "mule" (a person) carrying a backpack full of cocaine or heroin. Drugs are shipped in an amazing array of forms; for example, suspended in frozen fruit pulp being imported from Ecuador or in hollowed lumber from Brazil.


For a variety of reasons, there was pressure throughout the 1980s to increase the extent of military involvement in drug interdiction. The drug problem was viewed as a national crisis with an important international element. The military was seen as having unique capabilities, both of equipment and of training, to protect the borders.

The military had been ambivalent about entering the drug interdiction arena to any significant degree, seeing it as potentially corrupting and an inappropriate diversion from its primary mission. With the collapse of its principal strategic enemy, the Soviet Union, the U.S. military has become more willing to play a major interdiction role. This has been reflected in large increases to the military budgets to handle these new responsibilities. Current law prohibits arrests by military personnel. Accordingly, military participation has been con-fined to detection and monitoring rather than pursuit and apprehension.

The U.S. Navy provides a number of ships for interdiction patrols in both the Caribbean and the Pacific, combining training with a useful mission. The military runs the integrated radar and communication system that links the Customs Service, the Coast Guard, the Border Patrol, and other agencies. There have been no reports of significant problems of corruption associated with the military role in drug interdiction, but relations between the military and the civilian law-enforcement agencies with primary jurisdiction have sometimes been strained, the result largely of differences in organizational cultures.

With the proliferation of U.S. government units involved in interdiction, the need arose for coordinated command. The government has two Joint Inter-Agency Task Forces, one based in Key West, Florida, the other in Alameda, California. These task forces coordinate transit zone activities, including the U.S.-Mexico land border and air and maritime traffic along the borders and sea coasts. The U.S. Interdiction Coordinator is the Commandant of the U.S. Coast Guard.


Evaluation of the effectiveness of interdiction has been a vexed issue ever since the activity became prominent in the late 1970s. Very large quantities of drugs, particularly of cocaine, have been seized, but the size if such seizures has been cited both as evidence of success and of failure. It has been questioned whether more cocaine is being seized because interdictors are getting better at their job or because more cocaine is being shipped.

At a minimum, it would be desirable to express seizures as a fraction of total shipments (consumption plus seizures), but, unfortunately, estimates of consumption lack any systematic basis. Even expressed as a fraction of shipments, seizures are clearly an inadequate measure of the effectiveness of interdiction, since the program imposes two other costs on smugglersnamely, seizure of assets (e.g., boats, planes, real estate, and financial holdings) and the arrest and imprisonment of smuggling agents (e.g., crew members on ships, pilots, and couriers for financial transactions).

Reuter et al. (1988) suggest that the most appropriate measure is a price increase in the smuggling sector of drug distribution. Effective interdiction should raise smugglers' costs; the increase will be reflected in the difference between the price at which smugglers purchase drugs in the producer country (export price) and that at which they sell it in the importing country (import price). However, the process cannot serve as an operational criterion for any individual component of interdiction, since prices are set in a national market serviced by all modes and routes of smuggling. Anderberg (1992) concluded that the available data supported only inappropriate and/or inadequate measures of effectiveness, while any more cogent measure requires data that are not available and are not likely to be readily obtained.

One negative consequence of interdiction identified by Reuter et al. (1988) has received little attention. By seizing drugs on their way from the source country, interdiction may actually increase export demand for those drugs. As noted earlier, more stringent interdiction has two effects; it raises prices and thus reduces final demand in the United States, but it also increases the amount that must be shipped to meet a given consumption (because of a higher replacement rate). It appears that, based on reasonable assumptions about the cost structure of the cocaine trade, the second effect has proven greater than the first.


Interdiction clearly has had some important consequences for the drug trade in the United States. In contrast to the 1970s, little marijuana is now imported from Colombia, though that nation remains a low-cost producer. Successful interdiction, particularly against marine traffic from Colombia, has imposed such high costs on Columbian imports that now both Mexican and U.S. producers have come to dominate the U.S. market. Interdiction against Mexican-produced drugs is more difficult and thus the import price of Mexican marijuana is less than that of Colombian.

For cocaine there is much less evidence of success, though interdictors have certainly forced changes in modes of smuggling. In the early 1980s much of the cocaine was brought up by private plane directly from Colombia, but now most of it enters either by transshipment through Mexico or by commercial cargo. However, though interdictors now seize a large share of all shipments, they have not managed to prevent a massive decline in the landed price of the drug. Street prices of cocaine and heroin have dropped dramatically since the early 1980s.

The reasons for this limited success are not hard to find. Smugglers defray the risks of getting caught by carrying across very large quantities, so that the risks per unit smuggled are low. A pilot who charges 250,000 dollars for the risks (imprisonment, suffering injury or death in the course of landing) involved in bringing across a shipment of 250 kilograms is asking for only one dollar per gram, less than 1 percent of the retail price. Even if interdictors make smuggling much more risky, so that the pilot doubles the demand to 500,000 dollars, the higher fee still adds only another 1 percent to the retail price.

Moreover, it is difficult to make smuggling very risky when the nation is determined also to maintain the free flow of commerce and traffic. Hundreds of millions of people enter the country each year; cargo imports also amount to hundreds of millions of tons. Only a few hundred tons of cocaine need to be concealed in that mountain of goods and only a few thousand of those who enter need be in the smuggling business to ensure an adequate and modestly priced supply of cocaine.

Interdiction has accounted for a significant portion of federal government expenditures on drug control. By the end of the 1990s, many critics of the interdiction effort argued that these resources should be put into drug treatment programs and other programs that could reduce the demand for illegal drugs. Nevertheless, the U.S. government has remained committed to interdiction operations.

(See also: Border Management ; Dogs in Drug Detection ; Foreign Policy and Drugs ; International Drug Supply Systems ; Operation Intercept ; U.S. Government: The Organization of U.S. Drug Policy )


Anderberg, M. (1992). Measures of effectiveness in drug interdiction. Santa Monica, CA: The Rand Corporation.

Office of National Drug Control Policy. (1991). What America's users spend on illicit drugs. Washington, D.C.: U.S. Government Printing Office.

Office of National Drug Control Policy. (2000). National Drug Control Strategy: 2000 Annual Report. Washington, D.C.: U.S. Government Printing Office.

Reuter, P., Crawford, G., & Cave, J. (1988). Sealing the borders: The effects of increased military participation in drug interdiction. Santa Monica, CA: The Rand Corporation.

Peter Reuter

Revised by Frederick K. Grittner

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Drug Interdiction

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