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Jon Greenberg
By Jon Greenberg February 17, 2017

Are 27 million people trapped in modern slavery?

If the chair of the Senate Foreign Relations Committee Bob Corker, R-Tenn., has one special cause, it is ending modern slavery. In December, he won passage of a law that uses $50 million in federal money to seed a private foundation aimed at ending forced labor and human trafficking for the sex trade.

"It's illegal in every country in the world, including ours," Corker said on MSNBC’s Morning Joe on Feb. 15, 2017. "But, today, 27 million people, as we speak on this program, are enslaved."

That’s a big number, and we looked into the research behind it.

Corker acknowledged that hard data is, well, hard to find.

"Many human trafficking and modern slavery victims are part of a hidden population, which unfortunately makes it almost impossible to count with 100 percent accuracy just how many human beings are trapped around the world," Corker told us. "Fortunately, there are numbers of well-respected organizations that have done extensive work on this issue and give us a general sense of the magnitude of the problem."

One advocacy group Corker relied on is End It, which cited estimates ranging from 20 million to 45.8 million.

That’s quite a span, which suggests considerable differences of opinion as to what constitutes slavery and how to measure it.

Siddarth Kara, director of the Program on Human Trafficking and Modern Slavery at Harvard’s Kennedy School, told us the 27-million figure has been in circulation for years.

Kara gives more weight to the lower estimate of 20.9 million from the International Labor Organization’s 2012 report on forced labor. That study found that 4.5 million people were trapped by sexual exploitation. Another 14.2 million were locked in work that ranged from mining, to agriculture, to domestic service and manufacturing.

The situation is complex. They found that people such as migrant workers can move in and out of forced labor.

In Kara’s view, the truth lies between 20 and 40 million, and "closer to the International Labor Organization metric, I believe."

A key architect of the high-end estimate is Kevin Bales, professor of contemporary slavery at the University of Nottingham in England. Bales works closely with the Australian anti-slavery organization Walk Free to produce the Global Slavery Index. The index includes in its definition of slavery the same conditions as the International Labor Organization, but adds in child soldiers, child brides and other forced marriages.

Bales told us "the 45.8 million number is by far the most accurate." It is based, he said, on surveys and statistical models that have been checked against multiple measures.

But many long-time researchers of modern slavery strongly criticize the methods behind the Global Slavery Index.

"The trouble with this potentially admirable effort is that the data on which these tables rely is usually second-hand and often of seriously poor quality," wrote Neil Howard, a fellow at the European University Institute in Florence.

Howard studies labor exploitation in the West African nation of Benin, one of the highest-ranked trouble spots in the index. In an op-ed in the Guardian in 2014, he said the reality is different from the story told in the index.

"I worked with teenage boys who were said to be victims of trafficking and apparently forced from Benin to the artisanal quarries of Abeokuta, in Nigeria," Howard wrote. "The adolescent boys I interviewed willingly migrate to the quarries as part of a highly structured migrant network providing labor for the Beninese expatriate community that runs the quarry economy."

However, even ardent critics of the larger figures in the index still describe a problem that afflicts millions of people.

Joel Quirk, professor of political studies at the University of the Witwatersrand in South Africa, told us the overreach for hard data is rooted in the "huge market demand for numbers amongst journalists, government officials and the general public."

At the end of the day, Quirk said, "I would generally go with tens of millions" of people living in some form of slavery.

Our ruling

Corker said 27 million people are enslaved worldwide. He acknowledged that it is difficult to put a precise number on modern slavery. We found that different estimates defined slavery in different ways and used different methods to arrive at a number. Estimates range from 20 million to 46 million.

Among the experts we reached who question the higher estimates, we heard that Corker’s figure is in the right range. We rate this claim Mostly True.

Our Sources

MSNBC, Morning Joe, Feb. 15, 2017

Office of U.S. Senator Bob Corker, End Modern Slavery Initiative Act,

Office of U.S. Senator Bob Corker, Bill to launch End Modern Slavery Initiative to become law, Dec. 8, 2016

U.S. Senate, End Modern Slavery Initiative Act of 2015, Feb. 3, 2016

End It, home page, accessed Feb. 16, 2017

Global Slavery Index, Methodology, accessed Feb. 16, 2017

U.N. International Labor Organization, Global Estimate of Forced Labor, 2012

Guardian, The global slavery index is based on flawed data – why does no one say so?, Nov. 28, 2014

Guardian, Global slavery index researchers welcome constructive criticism, Jan. 15, 2014

Guardian, Keeping count: the trouble with the Global Slavery Index, Jan. 13, 2014

Open Democracy, The politics of numbers: the Global Slavery Index and the marketplace of activism, March 10, 2015

Walk Free, Modern slavery facts, accessed Feb. 15, 2017

Open Democracy, The dangerous appeal of the modern slavery paradigm, March 25, 2015

Theory, Culture and Society, Interview with Julia O’Connell Davidson on Modern Slavery, May 6, 2016

Washington Post, This map shows where the world’s 30 million slaves live. There are 60,000 in the U.S., Oct. 17, 2013

Email interview, Kevin Bales, professor of contemporary slavery, University of Nottingham, FEb. 15, 2017

Email interview, Joel Quirk, professor of political studies, University of the Witwatersrand, Feb. 16, 2017

Email interview, Siddarth Kara, Director, Program on Human Trafficking and Modern Slavery, Harvard Kennedy School, Feb. 16, 2017

Email interview, Bob Corker, Feb. 15, 2017

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