Professor Morris Kleiner co-authored “The Effect of Occupational Licensing on Earnings Inequality in the United States,” a research brief published  by the Cato Institute, a public policy research organization. 

The research examined how occupational licensing has affected earnings inequality in the U.S. from 1983 to 2019. Using data from the Current Population Survey, the study found a modest increase in the earnings gap between licensed and unlicensed workers with similar backgrounds. This widening gap was primarily driven by rising licensing premiums in high-paying occupations, with little market pressure to reduce these additional earnings over time.