Trafficking in human beings: a literature review

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2. Research questions 
Trafficking in human beings is a form of modern slavery non-institutionalized and that 
sometimes includes the trafficking of organs (Morehouse, 2008). In social and political 
debate, there is a lot of confusion about it, such as the difference between trafficking in 
human beings and smuggling of human beings and it is not often clear. At the time, it is an 
issue that weighs heavily on the international political agendas. First, because the victims 
are often exposed to situations of extreme physical and mental abuse, their rights are often 
violated and they are robbed of their dignity and freedom. Secondly because it appears to 
be, human trafficking, a major source of funding for organized crime (UNODC, 2009a). 
Although there have been researches on the issue, it is still difficult to give an accurate 
estimate of the incidence and prevalence of the problem. As already mentioned, is often not 
made a clear distinction between human trafficking and smuggling, so it creates a mix of 
data on human trafficking, smuggling in human beings and illegal immigration (Gallagher, 
2009). Further, governments and NGOs often use different methods and data to define the 
problem, creating a vicious cycle of confusion and discrepancies. Finally, there is a 
tendency to under-estimate the flows at the local and regional level (Kleeman, 2008).  
To get a good view of the studies on trafficking in human beings is needed a detailed 
analysis of the literature. However it is clear from a preliminary research that, in the past, 
no author made a clear assessment that focused exclusively on the analysis of the literature 
on human trafficking.  
This research is divided in two parts. The first part consists largely of a quantitative 
analysis of the literature analyzed, paying attention to the definitions used, to the topic 
discussed, to the period and to the methods used for data collection. The second part is a 
closer look at the regional distribution of the studies reviewed. The entire research points 
towards the answer of two main questions as an overall goal. The first one is: “What has 
been written since late 90s in the scientific and grey literature about trafficking in human 
beings?”. This question is further divided into other sub-questions: 
 
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 How is trafficking in human beings defined and to what extent does the literature 
make a difference between trafficking and smuggling in human beings? 
 Which forms of human trafficking have been particularly focused upon by the 
literature and which countries or regional contexts have been particularly focused 
upon by the literature? 
 Which topics and regional contexts are so far remained under-researched and on 
which topics and regional contexts should the future research focus on? 
 
The second question is: “What is the quality of the literature available?” and is 
divided into other sub-questions: 
 
 Which research methods have been most frequently used? 
 Which are the sources? 
 Which are the main strengths and weakness of the research methods used? 
 Which research methods should be used more intensively in the future 
 
This study does not intent to criticize but rather to review the literature on human 
trafficking. It is discussed what is known but more importantly emphasized what is not yet 
known and what the future research should be focused on. It seeks a valuable contribution 
to the literature.  
 
3. Purpose of the study 
 
This literature review is an attempt to analyze the existing state of knowledge on human 
trafficking and the expected contribution to the scientific knowledge. It focuses on books 
published by academics presses and articles published in scientific journals, international 
governmental organizations, non-governmental organizations, think tanks, governmental 
agencies, mass media sources but not on independent or freelance researchers.  
 
This research was build in a timeframe of about seven months, in order to select the 
relevant sources, summarize and evaluates the state of knowledge and to impose some 
intellectual order on the material. Only sources in English, Italian, French and Spanish were 
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selected. This research aimed to deconstruct and analyze the literature on human trafficking 
with a special focus on what has been written, the efforts undertaken to contain the problem 
and the quality of the literature available. After defining a specific timeframe from the late 
90s until 2010, the following analysis of the available literature permitted to evaluate 
quality, limits, caveats and strengths of the resources. Furthermore the most used research 
methods were analyzed. Consequently this led to an easy understanding of which countries 
or regional contexts have been particularly focused on in the literature and which topics 
were under-researched. Finally a database (Annex 1) was created to list the analyzed 
sources, organized by name of author; publisher; topic; country; number of pages; 
resources and research methods. 
 
4. Data collection and data analysis 
 
The literature on trafficking of human being is vast and often incoherent. This study 
consists of an analysis of 223 publications, selected and studied according to specific 
criteria: period, topic, type of publication and geographic relevance. Although there are 
undoubtedly more than 223 studies on human trafficking, should be stressed that no 
scientific study has ever been able to offer such an analysis. This constitutes the starting 
point for a database (Annex 1) organized by: the author's name; title; the object of the 
study; the geographic relevance and number of pages. The relevant studies have been 
published between the late 90s until 2010 and finally collected on the 2009 and on the 2010 
through various sources.  
 
 A major part of the literature has been found in academic and scientific on-line 
database. The access to the online resources was through Unodc Vienna Library; KU 
Leuven Library; JStor and Google scholar. Furthermore, the ProQuest database was found 
to be an important source of information. This source was chosen for its good reputation in 
the field of scientific studies. The researcher made use of specific keywords: “Human 
Trafficking”, “Trafficking in Human Being”,  “La trata de Seres Humanos”, “traite des 
êtres humains” and “Tratta di esseri umani” during the research in all the databases used. 
 
 
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The data that this study is based on are mainly scientific journals and official documents 
(reports, court files, statistical information), in order to do not have doubts about the 
credibility (often biased) and also because of their representativeness.  
 
5. Quality of the study 
 
 In this study, the researcher tried to collect and analyze the most high quality studies. 
However, there are several limitations associated with a literature review. The quality of the 
research is mainly determined by the quality of the scientific literature available, for this 
reason the selected studies were considered according to their scientific value. Despite this, 
it is not always easy to fully assess the quality of a study, the limited external validity 
and/or the generalization could be one of the problems that this study could encounter; due 
to the never-ending data on the issue and to the fact that many sources are in other 
languages, such as Chinese or Russian.  
 
 Another limitation of a literature review, the risk that many key resources are being 
neglected or that the access to certain data may be fully or partially restricted, especially for 
what concern governmental documents. This study is only for exploratory aims.  
 
 Further, in the study all the procedures are spelled out in order to increase the level of 
replication. In order to avoid traps and assure the quality of this research, the researcher 
looked at causal mechanism between the concepts and the findings, in order to move 
beyond the “common sense”. This study did not rely on interviews, firstly because the 
purpose of this study is a review of the existing literature on the topic and, secondly 
because experts could express their own interpretations of the phenomenon and so 
influence the objectivity and led to diverging interpretations. 
 
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CHAPTER II: Key findings of the literature review 
 
 This section presents the main results of the analysis of 223 studies. The chapter is 
divided into different levels: the analysis of the most common definitions and forms found 
in the literature, following a closer look at the timeframe of the studies reviewed and at the 
end an overview of the resources and research methods predominantly used. 
 
1. Definition 
 
There are many definitions of trafficking in human beings, but of 223 literature 
analyzed 168 studies (75.3 percent) referred to the definition of the United Nations (2000)1 
in the Convention on Transnational Organized Crime which includes a Protocol to Prevent, 
Suppress and Punish Trafficking in Persons, especially Women and Children (hereafter the 
Trafficking Protocol). It creates a common international understanding on what human 
trafficking is and how member states must address the problem. This is readily 
understandable given the fact that the literature analyzed until 2000, does not define the 
problem of human trafficking unambiguously and clearly, for example in Martin et al 
(2000): “[…] Smuggling is the term usually reserved for individuals and organizations 
who, for a fee, move individuals unlawfully over borders. Trafficking is normally defined as 
smuggling plus coercion or exploitation, as when women agree to be taken unlawfully 
across borders to be hostesses and wind up as prostitutes, or migrant workers wind up in 
slave or indentured conditions to repay smuggling fees […]”.   
 
Another example the definition used in the Europol Convention 1998, in Mameli 
(2002): “[…] Trafficking in human beings means subjection of a person to the real and 
illegal sway of other persons by using violence or menaces or by abuse of authority or 
intrigue with a view to the exploitation of prostitution, forms of sexual exploitation and 
assault of minors or trade in abandoned children […]” 
 
                                               
1
 United Nations 2000 Protocol to Prevent, Suppress and Punish Trafficking in Persons, Especially Women 
and Children, Supplementing the United Nations Conventions against Transnational Organized Crime 
(Palermo Protocol; A/RES/55/25). 
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The other studies reviewed after 2000 that did not make use of the UN definition (24.6 
percent), used a more general and simplistic definition: for example the Norwegian 
Government‟s Plan of Action to Combat Human Trafficking [2006–2009]: “[…] Human 
trafficking is a modern form of slavery and a serious form of crime that entails gross abuse 
of victims’ human rights […]”. 
 
The fact that a precise definition has been created and internationally recognized by 
governments has increased the chance to set the basis for policies and research that mainly 
stem from the same assumptions, but has also allowed a greater clarity on how to tackle the 
problem of trafficking, which is increasingly becoming a trans-national problem and 
therefore it must be fought in a more comprehensive and common approach. 
 
The United Nations definition 
 
Article 3. Use of terms 
 
For the purposes of this Protocol: 
 
(a) “Trafficking in persons” shall mean the recruitment, transportation, transfer, 
harbouring or receipt of persons, by means of the threat or use of force or other forms of 
coercion, of abduction, of fraud, of deception, of the abuse of power or of a position of 
vulnerability or of the giving or receiving of payments or benefits to achieve the consent of 
a person having control over another person, for the purpose of exploitation. Exploitation 
shall include, at a minimum, the exploitation of the prostitution of others or other forms of 
sexual exploitation, forced labour or services, slavery or practices similar to slavery, 
servitude or the removal of organs […]. 
 
The “Protocol to Prevent, Suppress and Punish Trafficking in Persons, especially 
Women and Children” defines the key elements of trafficking in persons as: 
 
 The act of recruitment, transportation, transfer, harbouring, or receipt of persons; 
 By means of the threat or use of force, coercion, abduction, fraud, deception, abuse