Illicit Wildlife Trade (IWT) is a serious global crime that negatively impacts biodiversity, human health, national security, and economic development. Many flora and fauna are trafficked in different product forms. We investigate a network interdiction problem for wildlife trafficking and introduce a new model to tackle key challenges associated with IWT. Our model captures the interdiction problem faced by law enforcement impeding IWT on flight networks, though it can be extended to other types of transportation networks. We incorporate vital issues unique to IWT, including the need for training and difficulty recognizing illicit wildlife products, the impact of charismatic species and geopolitical differences, and the varying amounts of information and objectives traffickers may use when choosing transit routes. Additionally, we incorporate different detection probabilities at nodes and along arcs depending on law enforcement’s interdiction and training actions. We present solutions for several key IWT supply chains using realistic data from conservation research, seizure databases, and international reports. We compare our model to two benchmark models and highlight key features of the interdiction strategy. We discuss the implications of our models for combating IWT in practice and highlight critical areas of concern for stakeholders.
more »
« less
This content will become publicly available on April 1, 2025
Multi-period max flow network interdiction with restructuring for disrupting domestic sex trafficking networks
We consider a new class of multi-period network interdiction problems, where interdiction
and restructuring decisions are decided upon before the network is operated and implemented throughout the time horizon.We discuss how we apply this new problem to disrupting domestic sex trafficking networks, and introduce a variant where a second cooperating attacker has the ability to interdict victims and prevent the recruitment of prospective victims. This problem is modeled as a bilevel mixed integer linear program (BMILP), and is solved using column-and-constraint generation with partial information. We also simplify the BMILP when all interdictions are implemented before the network is operated. Modeling-based augmentations are proposed to significantly improve the solution time in a majority of instances tested. We apply our method to synthetic domestic sex trafficking networks, and discuss policy implications from our model. In particular, we show how preventing the recruitment of prospective victims may be as essential to disrupting sex trafficking as interdicting existing participants.
more »
« less
- Award ID(s):
- 2039584
- PAR ID:
- 10385451
- Publisher / Repository:
- Springer US
- Date Published:
- Journal Name:
- Annals of Operations Research
- Volume:
- 335
- Issue:
- 2
- ISSN:
- 0254-5330
- Page Range / eLocation ID:
- 797-860
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Despite more than 40 years of counterdrug interdiction efforts in the Western Hemisphere, cocaine trafficking, or ‘narco-trafficking’, networks continue to evolve and increase their global reach. Counterdrug interdiction continues to fall short of performance targets due to the adaptability of narco-trafficking networks and spatially complex constraints on interdiction operations (e.g., resources, jurisdictional). Due to these dynamics, current modeling approaches offer limited strategic insights into time-varying, spatially optimal allocation of counterdrug interdiction assets. This study presents coupled agent-based and spatial optimization models to investigate the co-evolution of counterdrug interdiction deployment and narco-trafficking networks’ adaptive responses. Increased spatially optimized interdiction assets were found to increase seizure volumes. However, the value per seized shipment concurrently decreased and the number of active nodes increased or was unchanged. Narco-trafficking networks adaptively responded to increased interdiction pressure by spatially diversifying routes and dispersing shipment volumes. Thus, increased interdiction pressure had the unintended effect of expanding the spatial footprint of narcotrafficking networks. This coupled modeling approach enabled the study of narco-trafficking network evolution while being subjected to varying interdiction pressure as a spatially complex adaptive system. Capturing such co-evolution dynamics is essential for simulating traffickers’ realistic adaptive responses to a wide range of interdiction scenarios.more » « less
-
Legitimate companies are key facilitators of human trafficking. These corporate facilitators include not only websites providing advertisements for commercial sex services but also hotels and motels. Analysis of all active federal criminal sex trafficking cases in 2018 and 2019 reveals that in approximately 80% of these cases, victims were exploited at either hotels or motels. This paper studies the prevalence of the hospitality industry in the crime of sex trafficking and the failure of this industry to address this problem until recent civil suits were filed by victims against individual hotels and chains. Drawing on the civil cases filed in federal courts by victims of human trafficking between 2015 and 2021 along the East Coast of the United States, this paper assesses the characteristics of these hotels and the conditions in the hotels that facilitated sex trafficking. The paper then explores the moral and ethical problems posed by the facilitating role of hotel owners/operators in sex trafficking either through collusion or failure to act on and/or report evidence of individual abuse. Suggestions on how to address the problem are provided.more » « less
-
more » « less
Despite increased awareness of sex trafficking of minors in the U.S., prosecution of traffickers remains difficult, in part because of victim uncooperativeness. There are questions about how that uncooperativeness is expressed, whether it is evident in successfully prosecuted cases, and whether it is unique to trafficked minors or it emerges in similar age victims of sexual abuse. To provide insight relevant to these questions, we compared appellate opinions in two types of successfully prosecuted criminal cases: sex trafficking and sexual abuse of adolescent victims. In the trafficking opinions, victims were rarely described as disclosing on their own or as knowing their trafficker before the victimization. The opinions also often alluded to the trafficking victims’ uncooperativeness and delinquency history, and frequently mentioned electronic evidence and prosecution experts. The sexual abuse opinions, in contrast, tended to suggest that victims’ own disclosures initiated the case, perpetrators were known and trusted adults, and caregiver support during the case was common. Finally, the sexual abuse opinions never explicitly mentioned victim uncooperativeness or electronic evidence and rarely mentioned expert testimony or delinquency. The different characterizations of the two case types highlight the need for improved education concerning effective prosecution of sex crimes against minors.
-
more » « less
Abstract Long‐standing federal drug‐control policy aims to reduce the flow of narcotics into the USA, in part by intercepting cocaine shipments en route from South American production regions to North American consumer markets. Drug interdiction efforts operate over a large geographic area, containing complex drug trafficking networks in a dynamic environment. The extant interdiction models in the operations research and location science literature do not realistically model the objectives of and constraints on the interdiction forces, and therefore counterdrug organizations do not employ those models in their decision‐making processes. This article presents three new models built on the maximal covering location problem (MCLP): the maximal covering location problem for interdiction (MCLP‐I), multiple‐demand maximal covering location problem (MD‐MCLP), and multiple‐type maximal covering location problem (MT‐MCLP). These are novel formulations that permit multiple types of demands and facilities to be covered, and the utility of these formulations is demonstrated in the context of counterdrug operations. Optimal interdiction locations are determined within the geography of the Central American transit zone, using a coupled GIS and optimization framework. The results identify the optimal interdiction locations for known or estimated drug shipments and can constrain those optimal locations by differentiating among drug traffickers, the types of interdiction resources, and agency jurisdictions. This research both demonstrates the flexibility in designing alternative interdiction scenarios and presents novel covering models that may be extended to other application areas and operational contexts.
