Professor's constitutional guide for presidents

Every president has started his time in office with that oath of office, prescribed in the Article II of the United States Constitution, but while nearly every president has been accused of violating that oath, the frequency and range of accusations against President Trump inspired Corey Brettschneider, a constitutional law professor at Fordham Law and Brown University, to write the book "The Oath and the Office: A Guide to the Constitution for Future Presidents."