Cass Robert Sunstein FBA (born September 21, 1954) is an American legal scholar, particularly in the fields of constitutional law, administrative law, environmental law, and law and behavioral economics, who was the Administrator of the White House Office of Information and Regulatory Affairs in the Obama administration from 2009 to 2012. For 27 years, Sunstein taught at the University of Chicago Law School. Sunstein is the Robert Walmsley University Professor at Harvard Law School. He is Honorary Doctor at Copenhagen Business School.

Sunstein is a proponent of judicial minimalism, arguing that judges should focus primarily on deciding the case at hand, and avoid making sweeping changes to the law or decisions that have broad-reaching effects. Some view him as liberal, despite Sunstein's public support for George W. Bush's judicial nominees Michael W. McConnell and John G. Roberts, as well as providing strongly maintained theoretical support for the death penalty. Much of his work also brings behavioral economics to bear on law, suggesting that the "rational actor" model will sometimes produce an inadequate understanding of how people will respond to legal intervention. Sunstein has collaborated with academics who have training in behavioral economics, most notably Daniel Kahneman, Richard Thaler, and Christine M. Jolls, to show how the theoretical assumptions of law and economics should be modified by new empirical findings about how people actually behave. According to Sunstein, the interpretation of federal law should be made not by judges but by the beliefs and commitments of the U.S. president and those around him. "There is no reason to believe that in the face of statutory ambiguity, the meaning of federal law should be settled by the inclinations and predispositions of federal judges. The outcome should instead depend on the commitments and beliefs of the President and those who operate under him," argued Sunstein. Sunstein (along with his coauthor Richard Thaler) has elaborated the theory of libertarian paternalism. In arguing for this theory, he counsels thinkers/academics/politicians to embrace the findings of behavioral economics as applied to law, maintaining freedom of choice while also steering people's decisions in directions that will make their lives go better. With Thaler, he coined the term "choice architect."

What else did he mean
avoid making sweeping changes to the law or decisions that have broad-reaching effects.