This excerpt is from President Johnson's Impeachment trail.
When Andrew Johnson took upon himself the duties of his high office, he swore to obey the Constitution and take care that the laws be faithfully executed. That, indeed, is and has always been the chief duty of the President of the United States. The duties of legislating the laws of this country fall in no way to his lot...Having been sworn on the Holy Bible to obey the Constitution...he turns to the person administering the oath and says, "Stop; I have a further oath. I do solemnly swear that I will not allow the act entitled 'An act regulating the tenure of certain civil offices.' Just passed by Congress over the presidential veto, to be executed; but I will prevent the execution of the [tenure of certain civil offices] by virtue of my own constitutional power." How shocked Congress would have been--when sworn into office on that fatal day of March which made his the successor of Abraham Lincoln!
- Thaddeus Stevens, Closing arguments from Johnson Impeachment trail, 1868
What reason did the speaker in the excerpt give for the Impeachment of Andrew Johnson?