A third of the world's population resides in countries where democracy is in retreat, including India, Turkey, Brazil, Poland, Russia and the United States, researchers reported Thursday.
"While most people in the world still live in democracies in 2017, democracy has declined in 24 countries home to 2.6 billion people," they reported in the journal Democratization.
The drift toward autocratic rule -- under which checks against executive power are weakened -- occurred mainly in democratic regions, notably Western and Eastern Europe and the United States.
"Media autonomy, freedom of expression, and the rule of law have undergone the greatest declines," said lead author Anna Luhrmann, a political scientist at the University of Gothenburg in Sweden.
"This worrisome trend makes elections less meaningful across the world."
People in countries backsliding on liberal democracy by far outnumber those living in nations making progress, she noted.
The only region bucking the global trend is Africa, which has shown incremental but significant growth in democracy in recent years.
The study is based on the latest update of the Varieties of Democracy (V-Dem) dataset, a resource compiled by 3,000 experts worldwide that includes hundreds of variables and millions of data points reaching back half-a-century.
The database tracks changes in nearly 180 countries divided into four categories, depending on the robustness of their democratic institutions.
In "liberal democracies", uncorrupted multiparty elections are bolstered by a robust rule of law, an independent media, as well as strong judicial and legislative branches.
The next step down is "electoral democracies," in which these checks to strongman rule are less effective, even if elections remain reasonably free-and-fair.
- Africa bucks the trend -
Last year, just over half the world's population lived in one or the other of these systems, though only 14 percent resided in liberal democracies.
In "electoral autocracies," multiparty elections and limited civil liberties are undermined by repression, censorship and intimidation, while in "closed autocracies" outright dictatorship is, at best, dressed in a fig leaf of rigged elections.
Over the past decade, 20 countries have slipped a notch in the V-Dem ranking, including four in the European Union: Hungary, Poland, Lithuania and Slovakia were all downgraded from "liberal" to "electoral" democracies.
Israel, Mauritius and South Africa also strayed further from democratic ideals.
In 2017, "we are back to the global level of democracy recorded shortly after the end of the Soviet Union in 1991," the study found. "The last six years alone have unfortunately brought us back 25 years in time."
Among the 17 countries that transitioned upward since 2008 toward a more political system, Tunisia is the only one to move from autocracy to liberal democracy.
Four nations in sub-Saharan Africa -- Guinea Bissau, Ivory Coast, Malawi and Nigeria -- shifted from electoral autocracy to electoral democracy.
Globally, the percentage of people living in societies tending toward democracy increased gradually -- with the exception of central Europe and central Asia, which saw a sharp jump after the dissolution of the Soviet Union in 1991 -- from the late 1970s until around 2012.
Since then, it has declined in all regions, except Africa.
The study also found that two billion people lived in countries where wealthy elites gained more political power in the last ten years, including the United States.