In 1860, just before the outbreak of the American Civil War, the United States carried out a national census. One result was the very precise count of 3,953,761 slaves in the country, amounting to 12.6 percent of the total population. It was the last clear cut count of slavery in a national population in history.
Since the abolition of legal slavery, it has become a hidden and uncountable crime, making it hard to gauge the number of people truly affected. Globally, slavery takes many forms, with most slaves doing dirty, dangerous, demeaning work—digging and breaking rocks, shaping bricks by hand, cutting down forests with hand axes, or scrubbing floors.
Modern slavery is especially hard to measure compared to other crimes. This is something Walk Free and Hull University’s Wilberforce Institute has tried to change with the Global Slavery Index. By applying a method which was first used to estimate the number of fish in a Swedish fjord, and combining it with a survey of more than 25 countries, researchers have been able to get a widespread picture on the crime of slavery, from a global perspective.
The 2016 Global Slavery Index estimates there are 45.8 million people worldwide in slavery today. This is an increase on previous estimates of 36 million, but this does not necessarily mean that slavery is on the rise. Instead, the best way to view this figure is simply that the microscope is getting stronger, and better focused every year. This means we are now able to see slavery much more clearly, in places we weren’t able to in the past.
Counting a Crime
In criminology, the difference between the actual number of crimes and the officially reported number of crimes is called the “dark figure.“ There is a ”rule of dark figures” which states that the more serious the crime, the more likely it is to be reported to the authorities. For example, the dark figure for murder is normally far below 1 percent, but the dark figure for vandalism might be as high as 95 percent—so nearly everyone who experiences vandalism doesn’t bother to report it. This is a clear pattern in most countries, but there are two types of crime that often confound this rule.
Rape and sexual assault are very serious crimes, but are rarely reported to the police. This is primarily due to the social stigma attached to and felt by those who have been assaulted, along with the fear they might not be believed. Victims of slavery also feel stigma and shame, in part because sexual assault is very common in slavery cases. But slavery also defies measurement for a unique reason.
Normally, to determine the level of any specific crime in developed countries, the results of a national sample crime survey are compared to the official arrest and conviction rate. When being counted, all crimes are treated as “events”—also known as short single episodes—a mugging for example may only take one or two minutes.
But slavery is a crime which starts, and then continues for an indeterminate time—the victimization may last for days, months, or even years. This unique fact about slavery crime means it can rarely be measured using national crime surveys, as the victim is so often hidden away, enslaved, and not available to answer questions.
Understanding Slavery
This is what researchers are up against when they try to understand the scale of slavery across the world. In an attempt to combat this, for the slavery index, we cast the net wider and instead of just individuals, we surveyed households and families to see if anyone knew anyone who had experience of slavery.
Much like the 1860 U.S. Census, these surveys provide an estimate of the proportion of the population who are enslaved, and includes cases that happened in other countries. For example, respondents in national surveys in Nepal identified significant numbers of family members enslaved in Qatar and other Gulf States.
