The book "The Constitutional Presidency" explores the powers of the US President as outlined in the Constitution. It covers topics like the role of Article II, debates over presidential actions, and the influence of past presidents on the modern presidency. The authors argue that understanding the Constitution is crucial for evaluating presidential behavior. Key findings include discussions on executive power during the George W. Bush administration, the controversy surrounding the 2000 election, and the impact of military tribunals on the war on terrorism.