 Well, today we're talking about U.S. presidents who exploited their presidential power, the citizens who stopped them, and what we can learn from history that continues to repeat itself. Joining me from NPR Studios in New York is Corey Brettschneider. He's a professor of constitutional law and politics at Brown University. He's also author of the new book, The Presidents and the People, Five Leaders Who Threatened Democracy and the Citizens Who Fought to Defend It. Professor Brettschneider, welcome.