Cass Sunstein is an American legal scholar and professor known for his work in law and behavioral economics. He served as the Administrator of the Office of Information and Regulatory Affairs under President Barack Obama. Sunstein has written extensively on topics such as regulatory policy, constitutional law, and the impact of cognitive biases on decision-making. He co-authored the influential book Nudge with economist Richard Thaler, which explores how small changes in policy can significantly influence people's choices. Sunstein's research emphasizes the importance of understanding human behavior in crafting effective laws and regulations, making him a prominent figure in contemporary legal studies.