They are not, nor ever have been, pre-determined or natural classifications. As laws, land use regulations, as well as national and local power relations shift, so do the definitions of crimes and criminals . Thus, remote sensing cannot detect crime as it might detect a stand of a certain tree species: crimes, their perpetrators and their forms are defined by the dominant forces in society rather than spectral signatures or texture patterns. Because remotely sensed images are collected remotely , they lack detailed or nuanced definitions of crime drawn from the context of the landscapes they seek to analyze; they do not tell us why certain things happened or by whom, specifically. They leave understandings of causality and attribution to their interpreters. Despite the serious imbalances and problems that may arise from the remote sensing of crime, it continues apace, as we have seen from increasing discussions in the popular press and academic journals about the use of unmanned aircraft systems , increasing availability of micro-satellites and Google Earth images in the detection of crime . The continued and increasing use of remote sensing for these purposes brings us to the third limitation that we will mention here: the issue of validation. As remote sensing scholars, such as Jensen, Congalton and Foody note, validation is a critical part of any remote sensing exercise, and these scholars and others have laid forth strict protocols for validation exercises. Validating that crimes are actually occurring in the places that remote sensing algorithms say they are is not a simple task, however. On the ground, verification of potential illicit drug production, arms and drug smuggling or even illegal logging, flood table activities which are often protected by, or associated with, armed guards or agents, is often dangerous.
The lack of validation in the remote sensing of crime is troubling, however, because drastic military or police actions are often used to intervene where crimes are detected with lasting ecological, economic and social impacts: lives, security and livelihoods can be at stake, not to mention law enforcement credibility and resources. In short, classifying an action as a crime or a person as a criminal may have much higher costs than other classification mistakes. Thus, we must be doubly sure of what we classify as crime using remotely sensed images before we act. Further, such validation may add nuance and greater contextual understanding of the images used for analysis, which may allow for a more fair and balanced law enforcement response. Although all three of the above limitations are important to consider, this paper will take a methodological approach to engage with the issue of the validation of remotely sensed crime. We believe a focus on validation is critical, because as remotely sensed products become increasingly available to our desktops and smartphones, a rising trend of validation-free analysis is emerging. In these circumstances, products, like Google Earth, are used with the assumption that their images portray “the truth”, which should be acted upon. Despite the ease with which these data now flow to us, validation of our findings based on these images remains critical; competing sensors, processing methodologies and the familiarity of analysts with the limitations of the data they are using can present very real challenges to the ethical and accurate use of remote sensing in law enforcement and/or litigation. In this paper, we will first analyze how remote sensing technologies have been used to aid in the detection of crimes that might otherwise go undetected. As other authors have shown, “satellite imagery highlights the spatial footprint of human actors in very real and compelling ways” . Here, we review the literature that discusses how satellite and airborne technologies have been used in the active detection of felony cases of drug production, smuggling and extra-legal migrations.
We use the term “extra-legal” here, rather than “illegal,” in order to highlight the fact that though these acts are prohibited by USA or international law, the prohibition of these actions is often highly political and may not be deemed illegal in all cultures or by all groups. Forensic remote sensing has also been critical in the detection of environmental crimes, such as extra-legal mining and timber extraction, as well as in detecting oil spills and hazardous waste dumping. While the use of remote sensing in environmental forensics of this kind are important, many of the articles on these topics are embedded in larger land-clearance, deforestation and oceanographic literatures that deal with licit, illicit and accidental extraction or pollution, making the attribution of legality associated with the event difficult. Forensic remote sensing can also be used to identify the location of single and mass grave sites, but because most of these studies are experimental or historically oriented, we excluded them from our review. Remote sensing has also been used to find bodies, munitions and toxic waste that may have drifted based on water-current analysis. While our scope is narrower than that of forensic remote sensing, we do draw upon the advances in crime detection and validation that these studies have advanced in our analysis. Second, building on this literature review, we consider what kinds of validation protocols for the remote sensing of crime have been attempted and what the limitations to these protocols are, geographically, financially, as well as in terms of personnel and time. Third, we seek to generate a discussion on new and less traditional ways that crime may be sensed remotely or validated. While “first order” validation protocols, such as the collection of ground reference data, over flights and the use of higher spectral or spatial resolution images, are critical to assessing the accuracy of remotely sensed processes, they may not always be useful, possible or sufficient in the context of criminal investigations. Here, we propose going beyond the “first order” validation protocols that are standard in remote sensing to ensure accurate assessments of remotely sensed crime are occurring in ethical and contextually-situated ways. Here, we define the remote sensing of crime as the use of airborne and satellite remote imagery to detect crimes that have heretofore gone unreported or undetected. Lein describes forensic remote sensing as considering “the investigative use of image processing technology to support policy decisions regarding the environment and the regulation of human activities that interact with environmental process and amenities.” In this definition the term “forensic” refers to detailed investigation rather than a criminological one . As Lien points out, forensic remote sensing seeks to generate information pertaining to a specific event rather than “provide a broad thematic explanation”. As we note above, not all crimes are well suited to detection by remote sensing, however. Those crimes that have been most successfully detected using remote sensing technologies generally have the following three characteristics: first, they occur over relatively large geographic areas, so that their patterns may be easily detected, even with moderate or low spatial resolution imagery, like Landsat or MODIS ; second, the crimes or their evidence are generally visible for extended periods of time, allowing for their detection by satellites or airborne sensors over the length of a day, week or month; and third, they generally have characteristic spatial or spectral patterns that can be recognized from above using object-based analysis or spectral analysis.
This paper focuses on the utility of remote sensing in detecting crimes that are deemed a felony offense under U.S. federal law and are recognized as crimes internationally: arms, drug and human trafficking, 4×8 flood tray repeat extra-legal migration and drug production/possession . While there exists a plethora of academic papers that test methods that could theoretically be used for the remote sensing of crime—testing algorithms, detection techniques or spectral reflectances of illicit crops and smuggling trails—there are relatively few studies that document the use of remote sensing in the active reconnaissance of criminal activities. In this section, we review studies of active reconnaissance that exist in peer reviewed journals, as well as in gray literature in relationship to drug production, smuggling and extra-legal migrations. The characteristics of these activities fit those described above: they often occur in large geographic and temporal scales and may be uniquely identifiable from the surrounding landscape using aerial images. Because of these attributes, they represent the most common examples in papers regarding remote sensing used in the active detection of crimes. We reviewed 61 papers, reports from the United Nations Office on Drugs and Crime and master’s theses on these topics that were found through searches in the Google Scholar, Web of Science and Jstor search databases using a number of combined words and phrases . Some of these reports involved multiple case studies. Though, as Figure 1 shows, there were thousands of results that came from these combinations of search terms, very few of these results dealt with the active reconnaissance of crimes using remote sensing. We do acknowledge that there are probably many more reports and papers available on this topic in the law enforcement literature that are not available to the public. Government agencies, like Homeland Security, the Federal Bureau of Investigation and the Central Intelligence Agency, as well as international law enforcement agencies, like Interpol, may have extensive documentation on these topics that we were unable to access. Most prevalent in literature involving remote sensing of crime were studies on the detection of the cultivation of illicit substances. While the criminalization of each of these plants and their use is fraught with important political, cultural, economic and militaristic implications, an in-depth discussion of the reasoning behind these criminalizations and their ethics is beyond the purview of this article. Rather, we narrow our focus to the application of remote sensing products to actively detect “crime”, as it is construed by international or national governing powers. The use of remote sensing to detect the cultivation of illicit crops is a trend that has increased over time, perhaps because of the opening of the Landsat archives in 2008, and perhaps because of interest in opium growing in Afghanistan and South East Asia . We gathered the publicly available literature on the remote sensing of drug production in Afghanistan, Myanmar, Thailand, Laos, Bolivia, Colombia and Peru, countries targeted for drug production monitoring both by the UN’s Office of Drugs and Crime and academic researchers, due to these countries’ historically high exports of illicit substances . Using remote sensing to detect the growth of illicit drugs can be extremely helpful to those seeking to eradicate these plants, apprehend their cultivators, and limit the trade of the substances they produce. Unlike in-person surveys actually does conduct in some areas, which are labor intensive, time consuming, expensive, and potentially life threatening, remote sensing allows a small number of analysts to survey vast stretches of land to locate scattered sites of illicit crop production. Further, illicit crop detection methods that utilize remote sensing enable more frequent and complete surveys of the landscape than in-person surveys would. These techniques can focus the efforts of law enforcement officers, defoliant missions, and outreach programs. Remote sensing techniques may also allow governments and international groups to target drug production sites without putting their agents in harm’s way, or tipping off producers that some kind of action may be taken against them . Although the war on drugs began in the 1970s, the first publicly available papers we found on the active detection of illicit crop growth using remote sensing technologies were Sadler’s discussion of opium in Afghanistan and Chuinsiri and others’ detection of opium growth in Thailand. It was not until 1999 that groups like the UNODC’s Illicit Crop Monitoring Program began using remote sensing techniques to detect the growing of drug crops, particularly coca and opium poppies. The first UNODC cannabis survey was carried out in collaboration with the Afghan Ministry of Counter Narcotics and was not carried out until 2009. Like the criminalization of drug production, the criminalization of human movements across national borders either for migration or trade is also fraught with problematic social, political, economic, and militaristic issues and implications. Here, again, in-depth discussion of the reasoning behind these criminalizations and their ethics is beyond the purview of this article and we narrow our focus to the application of remote sensing products to actively detect “crime”, as it is construed by international or national governing powers.