In a study that relied on millions of health insurance claims, Professor Zack Cooper, director of the Tobin Center’s Health Care Affordability Lab, and Tobin Center Faculty Affiliate Professor Fiona Scott Morton found that 22% of patients who went to emergency departments within their health insurance networks were treated by an out-of-network doctor—often incurring major, unexpected expenses. The research caught the attention of the press and policymakers, kicking off a years-long debate about how to address “surprise medical bills.”