Modern Slavery: Meaning and Measurement

Principal Investigator

Professor Kevin Bales

Research Institution

University of Nottingham

Project Summary

This project has two key research aims. The first addresses the meaning of modern slavery. It is a study and analysis of how slavery is defined by different ‘user groups’, with the intention of bringing usability and clarity, and perhaps conformity and agreement, to the different needed types of definitions – specifically legal, operational, and popular definitions. A key part of this side of the research will be to bring the perspective and participation of contemporary survivors of slavery into the study through collecting survivor narratives first hand and introducing topics of definition into new interviews with survivors. 

The second key activity of this project addresses the measurement of modern slavery. It is a further test of the application of Multiple Systems Estimation techniques to the hidden population of slavery and trafficking victims, this time in the regional setting of Central Florida, USA, as a case study. The PI and the non-academic partner recently pioneered the first ever use of this technique in addressing slavery and trafficking crime in the UK with the result of the government altering their basis for policy and planning. In Central Florida, working with our NGOs, governmental, and law enforcement partners, the study will replicate the technique as a further test and demonstration.

It will also broaden this methodological research in two ways. Firstly, a journalist will be embedded into the MSE research process, exploring and interpreting the experiences of the participants to a wider audience, Secondly, as with our first sub-project, survivors of slavery/trafficking will take a key role in this research. We designed and planned the project in collaboration with two slavery survivors. 


For the past twenty years much forward movement in this field has been blocked by conflicts over definitions. Conferences, planning meetings, potential collaborations, even the drafting and enactment of laws, have foundered at early stages because definitions could not be agreed. While this work may not fully resolve this conflict, it is hoped that it might break the existing logjam, and allow a more free-flowing movement toward debate and consensus.

The impact of this will be felt in two key areas: firstly, the large number of existing legal definitions in national laws and international instruments which are not in harmony or contradictory, will be addressed by building a template definition. We are under no illusions that previous definitions now enacted as law will be scraped, but there is the possibility over time of amendment under the pressure of resolving jurisdictional disagreement. 

The impact of the sub-project testing and demonstrating Multiple Systems Estimation will be twofold. Firstly, just as the recent first use of MSE provided a more reliable estimation of slavery crime in the UK which then served as the basis for a re-think of government policy and enforcement, we intend that the same be true for those enforcing law, making policy, and serving survivors in Florida. Secondly, virtually all grounded planning and progress in this field, particularly in the developed countries, has been blocked by reliable prevalence estimates, and the impact of such a demonstration and dissemination of MSE would likely ripple out to other jurisdictions.

Contact Information

For further information email Kevin at