The Washington Post Live Q&As, March 3, 2010 by John Yoo
http://www.washingtonpost.com/wp-dyn/content/discussion/2010/03/03/DI2010030301148.html
I think men such as Washington, Lincoln or FDR broadly exercised their executive power because they genuinely saw terrible threats to American national security. They often did so knowing that their actions would be controversial and that they would provoke severe political reactions against them. They went forward anyway, giving presidential power, I argue in my book, a somewhat tragic quality.