Several of President Barack Obama’s judicial nominees face opposition on Capitol Hill, including a former U.S. Department of Justice lawyer whose work in the Office of Legal Counsel is under growing scrutiny.

The White House on Tuesday moved to quell concerns about David Barron, the former DOJ lawyer, who participated in the department’s legal analysis of the authority to use drones in the targeted killing of Americans abroad. Barron is up for a seat on the U.S. Court of Appeals for the First Circuit.