Many countries include impeachment in their constitutions, though the particulars may differ. For example, who may be impeached, the body allowed to initiate the proceedings, and the amount of votes required to convict the impeached official may vary. Usually, only a constitutional body has the right to initiate impeachment, and in most cases it is the legislative entity. The process is typically used only in the case of crimes committed by the official in question, not for simple mismanagement or unpopularity. An impeachment trial is similar in format to any other type of legal trial.
In some countries, such as Ireland, only the president may be impeached. In many other countries, any public official is subject to impeachment for crimes committed. In the United States, charges may be brought on both the federal and the state level. State impeachments are governed by individual state constitutions and initiated by state legislative bodies.
Impeachment is fairly rare in today's world. England, for example, has not used it since 1806. It is considered an extreme measure, only to be used in cases of extreme misconduct on the part of the official. Often, the threat of impeachment is enough to make an impact, such as when US President Richard Nixon resigned from office in 1974 under the threat of impending impeachment.
While 17 federal officers have been impeached in the United States since the country was founded, only seven were removed from office as a direct result of the proceedings. Andrew Johnson and Bill Clinton are the only presidents to have been impeached, in 1868 and 1998 respectively. The Senate, however, acquitted both men.
The impeachment of President Andrew Johnson was a result of political conflict and the rupture of ideologies in the aftermath of the American Civil War. It rose from uncompromised beliefs and a contest for power in a nation stuggling with reunity.
Before Abraham Lincoln was assassinated in 1865, he had formulated a plan of reconstruction that would be lenient toward the defeated South as it rejoined the Union. He planned to grant a general amnesty to those who pledged an oath of loyalty to the United States and agreed to obey all federal laws pertaining to slavery. (The exclusion to the general amnesty would be high-ranking Confederate officials and military leaders.)
Lincoln's plan also stated that when a tenth of the voters who had taken part in the 1860 election had agreed to the oath within a particular state, then that state could formulate a new government and start sending representatives to Congress.
Andrew Johnson was intent on carrying out this plan when he assumed the Presidency. This policy, however, did not sit well with certain radical Republicans in Congress who wanted to set up military governments and implement more stringent terms for readmission of the seceded states. As neither side was willing to compromise, a clash of wills ensued.
The political backing to begin impeachment came when Johnson breached the Tenure of Office Act by removing Edwin Stanton, Secretary of War, from his cabinet. The Tenure of Office Act had been passed over Johnson's veto in 1867 and stated that a President could not dismiss appointed officials without the consent of Congress.
The House of Representatives voted impeachment and the Senate tried the case. The trial lasted from March to May, 1868. In May, the Senate voted to acquit Andrew Johnson by a margin of 35 guilty to 19 not guilty - one vote short of the two-thirds needed