Page last updated July 16, 2023 by Doug McVay, Editor.

1. US Cocaine Seizure Effectiveness Rate, 2016-2020

"Methodology and Limitations

"Seizure data are obtained from OFO administrative records and is considered reliable. Estimates of the total cocaine flow are provided by the Defense Intelligence Agency (DIA).15 The U.S. Government does not have an estimate of the share of the total cocaine flow that passes through land POEs, but the U.S. Drug Enforcement Agency’s National Drug Threat Assessment states that the Southwest Border remains the key entry point for the majority of the cocaine entering the United States. The DIA estimate is based on a U.S. Government estimate of cocaine departing South America towards the United States, and additionally incorporates estimates of cocaine movement, cocaine production, and U.S. consumption derived from various U.S. Government agencies. The estimated amount of cocaine available to enter the United States (estimated flow in Table 15) is derived by finding the difference between the estimated amount of cocaine departing South America toward the United States and the sum of documented cocaine removals, consumption in the Transit Zone, and documented departures from the Transit Zone towards non-United States destinations.

"Available Data and Discussion

"Total seizures dropped to 19,000 kilograms in 2019, the lowest in the 2016-2020 period and down 35 percent from the 2016 to 2019 average. Land seizures dropped to 7,000 kilograms in 2019, the lowest in the period and down 18 percent from the 2016 to 2019 average. Estimated flow rose to 905,000 kilograms, but was still down 15 percent from the 2016 to 2019 average. The drop in total seizures and rise in estimated flows resulted in the seizure effectiveness rate halving from the previous year to 2.1 percent."

Department of Homeland Security. Border Security Metrics Report: 2021. April 27, 2022.

2. Definition of Drug Interdiction

"drug interdiction — A continuum of events focused on interrupting illegal drugs smuggled by air, sea, or land. Normally consists of several phases – cueing, detection, sorting, monitoring, interception, handover, disruption, endgame, and apprehension – some which may occur simultaneously.

"Department of Defense Dictionary of Military and Associated Terms," Joint Publication 1-02, Nov. 8 2010 (As Amended Through Aug. 15, 2012), p. 96.…

3. Ineffectiveness of Interdiction Efforts According to US Military Southern Command

"Last year, we had to cancel more than 200 very effective engagement activities in numerous multilateral exercises. Because of asset shortfalls, we’re unable to get after 74 percent of suspected maritime drug trafficking. I simply sit and watch it go by. And, because of service cuts, I don’t expect to get any immediate relief, in terms of assets to work with in this region of the world. Ultimately, the cumulative impact of our reduced engagement won’t be measured in the number of canceled activities and reduced deployments, it will be measured in terms of U.S. influence, leadership, relationships in a part of the world where our engagement has made a real and lasting difference over the decades."

Marine General John F. Kelly, Commander, US Southern Command, Testifying at a Hearing Before the US Senate Committee on Armed Services, Thursday, March 13, 2014, p. 6.

4. Estimated Worldwide Cocaine Seizures According to UNODC

"Trafficking in cocaine continued to increase in 2020 despite the COVID-19 pandemic, and global quantities \ of cocaine seized (not adjusted for purity) increased by 4.5 per cent, to a new record high of 1,424 tons, with quantities of cocaine paste and cocaine base seized rising by 16 per cent, to 108 tons, and quantities of cocaine hydrochloride seized rising by 4 per cent, to 1.105 tons (and only seizures of “crack” cocaine and non-specified types of cocaine showing smaller growth rates). Overall, estimates of global quantities of cocaine manufactured and seized show a strong positive correlation (with a correlation coefficient of 0.88 between 2005 and 2020),20 suggesting that the interception of cocaine has kept pace with the increasing supply of and trafficking in cocaine. In fact, long-term data indicate that quantities of cocaine seized have increased far more than quantities manufactured, although the comparability of the two data sets is limited by the potentially varying levels of purity of seized quantities over time. Between 2010 and 2020, global potential cocaine manufacture, expressed in 100 per cent purity, rose by 75 per cent, while global quantities seized (not adjusted for purity) rose by 125 per cent.21 Uncertainty regarding the purity of seized cocaine across all countries prevents a precise calculation of interception rates, but the data suggest that they increased, although not by enough to reduce the amount of cocaine available for consumption.

"Longer-term increases in global cocaine seizures show a clear upward trend over the past two decades, notably in the period 2015–2020, primarily driven by a shift towards seizures made in South America, notably in the countries where most of the cocaine manufacture takes place. The total quantity seized in South America is now five times as high as in North America, in contrast to the period 1999–2001 when overall cocaine seized in North America was higher than in South America. At the same time, data also show a shift from the Caribbean towards Central America in terms of the quantity of cocaine seized over the last two decades, reflecting a general shift towards trafficking cocaine from Colombia along the Pacific route to Central America and North America instead of via the Atlantic Ocean and the Caribbean.

"North America, the world’s largest consumer market for cocaine, reported strong increases in seizures of the substance in the period 2015–2020, as did Europe, the second largest consumer region, up to and including 2019, before stabilizing in 2020. Total quantities of cocaine seized in Asia and Africa peaked in 2019, while quantities seized in Oceania continued to trend upwards in 2020."

UNODC, World Drug Report 2022 (United Nations publication, 2022).

5. Cocaine Smuggling to the US

"In the Americas, the primary cocaine trafficking flow is from Colombia to the United States. The analysis of cocaine seizure samples in the United States mainland suggests that 90 per cent of that cocaine originated in Colombia and 6 per cent originated in Peru, while the origin of the rest was unknown.40

"Cocaine seizures in North America tripled over the period 2014–2018, from 91 tons in 2014 to 272 tons in 2018. The main destination country for cocaine shipments continues to be the United States. Overall, cocaine seizures reported by the United States increased by 14 per cent to 254 tons.41 However, most of those seizures took place outside the United States mainland, where they increased. By contrast, cocaine seizures reported by United States Customs and Border Protection fell from 34 tons in 2017 to 27 tons in 2018, including the reported decreases in seizures along the south-western border, and “drug removals” reported by the DEA, covering seizures made within the territory of the United States, which dropped from 114 tons in 2017 to 93 tons in 2018. This decrease in seizures may have been the result of significant seizures being effected by the United States authorities prior to the cocaine’s arrival in the United States, as well as a combination of changes in trafficking and supply patterns and an overall law enforcement focus on opioids.42 The largest DEA “cocaine removals” at the state level in 2018 were, however, still those reported by states and territories, notably California, Texas, Florida, Georgia and Puerto Rico, all of which are in southern parts of the United States or have a southern border, in addition to the State of New York, in the northeast.43 At the same time, the availability of cocaine was perceived to have declined slightly among the general population in the United States in 2018 as compared to a year earlier.44 This suggests that declines in seizures within the United States in 2018 may indeed have been primarily a reflection of a decrease in cocaine trafficking taking place within the country.

"The main trafficking flow of cocaine still goes from the drug’s major production centres in Colombia, either by sea, in particular via the Pacific Ocean, to Central America or to Mexico, or through Ecuador (mainly for cocaine manufactured in southern Colombia) or by land to Central America (mainly for cocaine manufactured in northern Colombia) and onwards to Mexico45 from where it enters the United States across the south-western border, which is the section of the border where most seizures of cocaine by the United States authorities are made.

"The Pacific route and, to a lesser extent, the Atlantic route remain the two main trafficking routes from Colombia to North America, while trafficking by air and mail continues to be comparatively limited."

World Drug Report 2020. Booklet Three: Drug Supply. June 2020. United Nations publication, Sales No. E.20.XI.6).

6. Heroin Smuggling to the US

"On the basis of seizure data, heroin trafficking within the Americas, in particular to the United States, appears to have increased over the past decade. Quantities of heroin and morphine seized reported in the Americas rose from 4 per cent of the global total (excluding seizures made in Afghanistan) in 2008 to 9 per cent in 2018.

"Most heroin (and morphine) trafficking in the Americas continues to take place within North America, i.e., from Mexico to the United States and, to a far lesser extent, from Colombia and from Guatemala (typically via Mexico) to the United States. Based on forensic profiling, United States authorities estimated in 2017 that over 90 per cent of the heroin samples analysed originated in Mexico and 4 per cent in South America, while around 1 per cent originated in South-West Asia. This stands in stark contrast to a decade earlier (2007), when only 25 per cent was sourced from Mexico and 70 per cent was imported from South America.14"

World Drug Report 2020. Booklet Three: Drug Supply. June 2020. United Nations publication, Sales No. E.20.XI.6).

7. Global Opiate Seizures

"Despite a 19 per cent decline in the quantity of opiates seized globally from 2017 to 2018 (calculated on the basis of converting those seizures into heroin equivalents), dropping to 210 tons, that was still the third highest amount ever reported and continued to exceed the quantity of pharmaceutical opioids seized.2 The overall decline in the quantity of opiates seized in 2018 was mostly due to a decrease by half in the quantity of morphine seized. The quantity of opium and heroin seized, by contrast, remained rather stable in 2018 (+2 per cent for opium; and -6 per cent for heroin on a year earlier).

"The opiate seized in the largest quantity in 2018 continued to be opium (704 tons), followed by heroin (97 tons) and morphine (43 tons). Expressed in heroin equivalents, however, heroin continued to be seized in larger quantities than opium or morphine. Globally, 47 countries reported opium seizures, 30 countries reported morphine seizures and 103 countries reported heroin seizures in 2018, suggesting that trafficking in heroin continues to be more widespread in geographical terms than trafficking in opium or morphine.

"The quantities of opium and morphine seized continued to be concentrated in just a few countries in 2018, with three countries accounting for 98 per cent of the global quantity of opium seized and 97 per cent of the global quantity of morphine seized. By contrast, seizures of heroin continue to be more widespread, with 54 per cent of the global quantity of heroin seized in 2018 accounted for by the three countries with greatest seizures."

World Drug Report 2020. Booklet Three: Drug Supply. June 2020. United Nations publication, Sales No. E.20.XI.6).

8. Misleading Official Statistics on Interdiction and Seizures

"Comparing absolute numbers of total cocaine seizures and manufacture could be misleading. To understand the relationship between the amount of annual seizures reported by States (694 tons cocaine of unknown purity in 2010) and the estimated level of manufacture (788-1,060 tons of cocaine of 100 per cent purity), it would be necessary to take into account several factors, and the associated calculations would depend on a level of detail in seizure data that is often unavailable. Making purity adjustments for bulk seizures, which contain impurities, cutting agents and moisture, to make them directly comparable with the cocaine manufacture estimates, which refer to a theoretical purity of 100 per cent, is difficult, as in most cases the purity of seized cocaine is not known and varies significantly from one consignment to another. The total amount of seized cocaine reported by States is also likely to be an overestimation. Large-scale maritime seizures, which account for a large part of the total amount of cocaine seized, often require the collaboration of several institutions in a country or even in several countries.76 Therefore, double counting of reported seizures of cocaine cannot be excluded."

World Drug Report 2012. UN Office on Drugs and Crime. United Nations publication, Sales No. E.12.XI.1.

9. Trends in Cocaine Trafficking

"While their decline began in 2005, cocaine seizures in the United States have followed a downward trend similar to the prevalence of cocaine itself, suggesting that falling seizures reflect a decreasing supply of cocaine reaching the United States. One reason contributing to the time lag that emerges from these similar, but unsynchronized, trends, with changes in seizure data occurring earlier than changes in prevalence data, is that seizures usually occur relatively near to the start of the trafficking cycle, whereas consumption usually takes place at its end."

UNODC, World Drug Report 2012 (United Nations publication, Sales No. E.12.XI.1), p. 37.…

10. Cocaine Trafficking to Europe

"In contrast to North America, where prevalence of cocaine use and cocaine seizures have fallen in parallel, the stability of the prevalence of cocaine use in Western and Central Europe has not coincided with stable seizure levels, as the seizure levels have fallen by some 50 per cent since 2006. A report of the European Police Office (Europol) on maritime seizures of cocaine suggests that a change in trafficking modes could have contributed to this apparent mismatch.82 While overall seizures have decreased, the amount of cocaine seized in containers has actually increased in countries covered by the study, such as Germany, Spain and the United Kingdom. Seizures of cocaine found on vessels (but not inside containers) have decreased over the same period, implying that traffickers are increasingly making use of containers on the European route by taking advantage of the large volume of container shipments between South America and Europe.83 Semi-submersible boats, which are known to be used on the Pacific route, do not yet play a role in transatlantic trafficking.84 Meanwhile, the West African route, which became more and more popular up until 2007, has since become less important."

UNODC, World Drug Report 2012 (United Nations publication, Sales No. E.12.XI.1), p. 38.…

11. Cocaine Markets Expanding

"An even greater increase in cocaine seizures can be seen in East Africa and Oceania, where the 2009/2010 levels were about four times higher than in 2005/2006, and in East and South-East Asia. In Oceania (2.6 per cent and increasing in Australia and 0.6 per cent in New Zealand), annual prevalence of cocaine use is high compared with South-East Asian countries (Indonesia, Philippines and Thailand), where less than 0.1 per cent of the adult population use cocaine. However, for many Asian countries, including China and India, no recent information on cocaine use is available. Limited information from Africa suggests that cocaine trafficking via West Africa may be having a spillover effect on countries in that region, with cocaine use possibly emerging alongside heroin use as a major problem among drug users."

UNODC, World Drug Report 2012 (United Nations publication, Sales No. E.12.XI.1), p. 40.…

12. Global Opiate Seizures

"The world only intercepts one fifth of the global opiate flows every year, with very mixed performances at the country level. The Islamic Republic of Iran has the highest seizures rate, at 20 per cent. Next are China (18 per cent) and Pakistan (17 per cent). In the two main source countries, Afghanistan and Myanmar, seizures represent only 2 per cent each of the world total. An equally insignificant 2 per cent is seized in South-Eastern Europe, the last segment of the Balkan route to Europe. Along the Northern route (Central Asia - Russia), the interception rate is also low (4-5 per cent)."

United Nations Office on Drugs and Crime, "Addiction, Crime and Insurgency: The transnational threat of Afghan opium" (Vienna, Austria: October 2009), p. 7.…

13. US Customs and Border Protection Agency

"CBP is actually the largest law enforcement organization in the United States, comprised of 20,000 Border Patrol agents deployed between the ports of entry and over 20,000 CBP officers actually stationed at the various land, air, and sea ports of entry throughout our country. They are joined by an 1,000-agent force of air and marine interdiction agents, whose job it is to implement the air and maritime responsibilities of CBP. There are an additional 2,300 agricultural specialists and other professionals that bring the sum total of CBP staffing, as is reflected in the chart,2 to over 58,000 individuals."

Tomsheck, James F., "New Border War: Corruption of U.S. Officials by Drug Cartels," Hearing before the Ad Hoc Subcommittee on State, Local, and Private Sector Preparedness and Integration, of the Senate Committee on Homeland Security and Government Affairs, (Washington, DC: US Senate, May 10, 2010), p. 6.…

14. Customs and Border Protection Agency, 2009

"In fiscal year 2009 alone, CBP processed more than 360 million pedestrians and passengers, 109 million conveyances, apprehended over 556,000 illegal aliens between our ports of entry, and encountered over 224,000 inadmissible aliens at our ports of entry. We also seized more than 5.2 million pounds of illegal drugs. Every day, CBP processes over 1 million travelers seeking to enter the United States by land, air, or sea."

Frost, Thomas M., "New Border War: Corruption of U.S. Officials by Drug Cartels," Hearing before the Ad Hoc Subcommittee on State, Local, and Private Sector Preparedness and Integration of the Committee on Homeland Security and Government Affairs, (Washington, DC: United States Senate, May 10, 2010), pp. 6-7.…

15. Ineffectiveness of Interdiction Spending

"In 2005, the federal government spent $2.6 billion to disrupt and deter the transport of illicit drugs into the United States. While international efforts to step up drug seizures may affect availability, price and consequences associated with a particular drug (i.e., cocaine or heroin), CASA was unable to find evidence that such strategies have an overall impact on reducing substance abuse and addiction or its costs to government."

National Center on Addiction and Substance Abuse at Columbia University. Shoveling Up II: The Impact of Substance Abuse on State Budgets. New York, NY: CASA, May 2009.

16. Interdiction Funding Request from US President's FY2017 Drug Control Budget

"The United States continues to face a serious challenge from the large scale smuggling of drugs from abroad that are distributed to every region of the Nation. In FY 2017, the Administration’s request includes $4.1 billion to support the efforts of Federal LEAs, the military, the intelligence community, and our international allies to support collaboration to interdict or disrupt shipments of illegal drugs, their precursors, and their illicit proceeds. The FY 2017 request represents a decrease of $341.4 million, (7.6 percent) below the FY 2016 enacted level. The major efforts are highlighted below.
"Customs and Border Protection ($2,400.4 million)
"Department of Homeland Security
"Customs and Border Protection (CBP) implements border enforcement strategies to interdict and disrupt the flow of narcotics and other contraband across our Nation’s borders. The comprehensive interdiction strategy includes the border security personnel at and between ports of entry (POE), detection and monitoring provided by aviation assets, and border security infrastructure and technology.
United States Coast Guard ($1,269.0 million)
"Department of Homeland Security
"One facet of the United States Coast Guard’s (Coast Guard) mission is maritime interdiction. The Coast Guard functions as the maritime counternarcotics presence in the source, transit, and arrival zones. Their maritime interdiction activities disrupt the flow of drugs into the United States.
"Federal Aviation Administration Interdiction Support ($12.6 million)
"Department of Transportation/Federal Aviation Administration
"Air traffic controllers staffing Air Route Traffic Control Centers monitor the Air Defense Identification Zones to detect possible suspicious aircraft movement. When suspicious movement is identified, the Federal Aviation Administration (FAA) notifies the DEA and Coast Guard of such activity. Upon confirmation of suspicious aircraft movement, FAA controllers support interdiction efforts by providing radar vectors to track the time of arrival, traffic advisory information, and last known positions to intercept aircrafts of interest.
"Department of Defense Drug Interdiction ($435.5 million)
"Department of Defense
"DoD’s counterdrug programs detect, monitor, and support the disruption of drug trafficking organizations. Additionally, DoD coordinates interagency resources and force requirements of air and surface assets in the Western Hemisphere Transit Zone."

FY 2017 Budget and Performance Summary - Companion to the National Drug Control Strategy, Executive Office of the President, Office of National Drug Control Policy, December 2016, p. 17.…

17. Cocaine Transshipment Through Mexico

"The US authorities estimate that around 90% of the cocaine, which entered their country in 2006, transited the Mexico-Central America corridor. The amounts of cocaine trafficked into the United States declined, however, in 2006 and this trend became more pronounced in 2007 as Mexican authorities stepped up efforts to fight the drug cartels operating on their territory, which also increased the level of cocaine related violence in Mexico. US cocaine seizures along the country’s southern border declined by 20% over the first two quarters of 2007 on a year earlier and by almost 40% in the second quarter of 2007, as compared to the second quarter of 2006. The main entry point of cocaine into the United States continues to be the common border of Mexico with southern Texas (accounting for a third of all seizures along the border with Mexico in 2006), followed by the border with southern California (18%).14"

United Nations Office on Drugs and Crime, "World Drug Report 2008" (United Nations: Vienna, Austria, 2008), p. 77.…

18. Transshipment Through Mexico

"As Mexican traffickers wrested control of the most valuable portions of the trafficking chain from the Colombians, Mexico itself has become by far the most important conduit for cocaine entering the United States. Today, some 200 mt of cocaine transits Central America and Mexico annually, bringing some US$6 billion to the regional 'cartels'. As a result, those who control the portions of the Mexican border through which the bulk of the drug passes have gained wealth and power comparable to that commanded by the Colombian cartels in their heyday. These groups command manpower and weaponry sufficient to challenge the state when threatened, including access to military arms and explosives."

UNODC, World Drug Report 2010 (United Nations Publication, Sales No. E.10.XI.13), p. 237.…

19. Reliance on Interdiction Backfires

"One flaw of current U.S.-Mexico strategy is the false presumption that international trafficking of drugs, guns, and cash can be effectively addressed through interdiction, particularly along the nearly two thousand- mile U.S.-Mexico border. After a three-decade effort to beef up security, the border is more heavily fortified than at any point since the U.S.-Mexico war of 1846–48. The United States has deployed more than twenty thousand border patrol agents and built hundreds of miles of fencing equipped with high-tech surveillance equipment, all at an annual cost of tens of billions of dollars. Although this massive security buildup at the border has yielded the highest possible operational control, the damage to Mexico’s drug cartels caused by border interdiction has been inconsequential.43 Meanwhile, heightened interdiction at the border has had several unintended consequences, including added hassles and delays that obstruct billions of dollars in legitimate commerce each year, the expansion and increased sophistication of cross-border smuggling operations, and greater U.S. vulnerability to attacks and even infiltration by traffickers.44 Further efforts to beef up the border through more patrolling and fencing will have diminishing returns, and will likely cause more economic harm than gains in security for the struggling communities of the border region.45"

Shirk, David A., "Drug War in Mexico: Confronting a Shared Threat," Council on Foreign Relations, Center for Preventive Action (Washington, DC: March 2011), p. 18.…

20. TCOs Deal With Interdiction Through Overproduction

One of the major problems with supply reduction efforts (source control, interdiction, and domestic enforcement) is that, "suppliers simply produce for the market what they would have produced anyway plus enough extra to cover anticipated government seizures."

Rydell, C.P. & Everingham, S.S., Controlling Cocaine, Prepared for the Office of National Drug Control Policy and the United States Army (Santa Monica, CA: Drug Policy Research Center, RAND, 1994), p. 6.…

21. Global Seizures of Heroin and Illegal Morphine

"The total quantity of heroin seized globally reached a record high in 2016, while the quantities of opium and morphine seized reached the second highest level ever reported. The largest quantities of opiates seized were of opium (658 tons), followed by seizures of heroin (91 tons) and morphine (65 tons). Overall seizures of opiates, expressed in heroin equivalents, increased by almost 50 per cent from 2015 to 2016, of which the quantity of heroin seized exceeded that of opium and morphine.

"As most seizures of opiates are made in, or close to, the main opium production areas, Asia, which is responsible for more than 90 per cent of global illicit opium production, accounted for 86 per cent of the total quantity of heroin and morphine seized in 2016. This is primarily a reflection of the increasing concentration of opium production in Afghanistan and the consequent increase in seizures by neighbouring countries.

"Similarly to the distribution of heroin and morphine seizures, overall, 90 per cent of the total quantity of opiates (including opium), expressed in heroin equivalent, was seized in Asia, the vast majority in the Near and Middle East/South-West Asia (83 per cent), while 6 per cent was seized in East and South- East Asia."

World Drug Report 2018. United Nations publication, Sales No. E.18.XI.9.…

22. Interdiction Estimate Accuracy

"As far as trafficking is concerned, a comparison with the interception rate of opiates in 1998 (17%), makes the interception rate of 46% reported for cocaine for the same year appear extremely high. Assuming a similar volume of seizures in 1999, the rate would be even higher (50%). For the reasons mentioned above, there are thus some doubts about the accuracy of the total potential cocaine production reported during the past few years (765 mt in 1999)."

United Nations Office for Drug Control and Crime Prevention, Global Illicit Drug Trends 2000 (New York, NY: UNDCP, 2000), p. 32.…

23. Interdiction - Terrorism - 9-11-11

"Since the late 1990s, the US policy has linked its counternarcotics policy with counterterrorism policy in Afghanistan. However, there is modest proof of a direct involvement by Al Qaida in the international drug trafficking network. The 9-11 Commission found little evidence to confirm this accusation. Groups known to be involved in the illicit drug economy were rather the Sunni Hizb-i Islami group of Gulbuddin Hekmatyar and the Taliban. [37] However, according to the World Bank and UNODC, the Taliban derived more income and foreign exchange in the period 1996-2000 from taxing smuggled goods from Dubai to Pakistan than from the drug industry. Even now, the Taliban have several sources of income and they are not economically dependent on the narcotics trade only. [38] This reality, however, has not stopped the United Nations Office on Drugs and Crime to argue that “fighting drug trafficking equals fighting terrorism”.[39]"

Corti, Daniela and Swain, Ashok, "War on Drugs and War on Terror: Case of Afghanistan," Peace and Conflict Review (San Jose, Costa Rica: University for Peace, 2009) Volume 3, Issue 2, p. 5.…

24. Wholesale Price of Heroin in 2010

In 2010, a kilogram of heroin typically sold for an average wholesale price of $2,527.60 in Pakistan. The 2010 wholesale price for a kilogram of heroin in Afghanistan ranged around $2,266. In Colombia, a kilogram of heroin typically sold for $10,772.3 wholesale in 2010. In the United States in 2010, a kilogram of heroin ranged in price between $33,000-$100,000.

UN Office on Drugs and Crime, World Drug Report 2012 (United Nations publication, Sales No. E.12.XI.1), Opioids: Retail and wholesale prices by drug type and country (2010 or latest available year)……

25. Drug Detection Dogs

"The overwhelming number of incorrect alerts [by drug and/or explosive detection dogs] identified across conditions confirms that handler beliefs affect performance. Further, the directed pattern of alerts in conditions containing a marker compared with the pattern of alerts in the condition with unmarked decoy scent suggests that human influence on handler beliefs affects alerts to a greater degree than dog influence on handler beliefs."
"In conclusion, these findings confirm that handler beliefs affect working dog outcomes, and human indication of scent location affects distribution of alerts more than dog interest in a particular location."

Lit, Lisa; Schweitzer, Julie B.; Oberbauer, Anita M., "Handler beliefs affect scent detection dog outcomes," Animal Cognition (Heidelberg, Germany: January 2011), Volume 8, Number 3, pp. 202 and 204.…