Unskilled workers living in places such as India and Nepal may pay fees equaling a year’s salary to labor recruiters in their homelands to get jobs in gulf countries. The workers then fall into debt because, to pay those fees, they take out loans from recruiters at interest rates of 30 percent or more.

But the jobs they get may be different from and pay less than the ones they were promised. And workers are effectively chained to those positions because they need permission from their employers to change jobs.

After reports by human rights groups and a series of articles in The Guardian, Qatar hired DLA Piper in 2013 to examine the country’s labor practices and make recommendations for changes.

Officials in Qatar have said that companies building World Cup stadiums will be held to higher standards of worker treatment, and proposed changes to the kafala system are undergoing legislative review. In a statement, a government spokesman said the country had also put into place other safeguards, such as electronic payment of workers’ salaries, and had built modern accommodations for migrant laborers.

Mr. Pullen, the former DLA lawyer, said he believed Qatar had taken steps to improve conditions but added that the pace of change remained slow and that it was impossible to know, given the country’s lack of transparency, how much of the kafala system it planned to change.

Labor activists and officials in Qatar are also making competing claims about the scope and causes of migrant worker deaths in the country. Experts say both sides are making contentions that appear to have little foundation.

In a 2014 study, the International Trade Union Confederation, a labor group, estimated that 4,000 migrant workers could die before the start of the 2022 World Cup. To reach that figure, the group took the number of deaths of workers from India and Nepal reported to those countries’ embassies in Qatar over a three-year period and extrapolated that figure against a projected increase of 500,000 foreign laborers in Qatar’s work force in coming years.