How to impeach a sitting President

What actually needs to happen to impeach a sitting President, and what happens if proceedings are actually initiated?

First, there has to be an actual crime. The Constitution says that a sitting President can be impeached for "high crimes and misdemeanors". What constitutes a "high crime" isn't exactly clear, but it probably means what are now denominated as "felonies". It needn't be a federal crime, it could be a state crime.

Hence, for example, when President Clinton allegedly lied under oath in a deposition in the Paula Jones' case about his actions with Monica Lewinsky, that would be perjury (had he not been acquitted), that's a crime (in that case, a state crime), and that qualifies.

Taking an unpopular action, or failing to take a popularly demanded action, is not necessarily a crime, unless one is required to act (or fail to act) by law. So, 99.9% of what any sitting President does is not actionable in impeachment proceedings, regardless of whether we do or don't like it.

Next, the House of Representatives has to pass a bill of impeachment. This puts the House in the position of sitting as a sort of Grand Jury, examining the evidence to see if there is sufficient evidence to prosecute the claim, regardless of whatever defenses might be available. Hence, President Clinton was impeached, as was President Johnson (Andrew, not Lyndon), by the House of Representatives. Being impeached does not mean that one is actually guilty (nor does being indicted by a Grand Jury).

If the House passes the bill of impeachment, the case moves to the Senate. The Senate holds a trial, with the Chief Justice of the United States Supreme Court presiding (normally, the Vice President, acting as President of the Senate, presides over Senate proceedings; this is an exception).

"Presiding", to my understanding, means that the CJ makes evidentiary rulings and governs the proceedings, but as far as I'm aware, the CJ has no vote on the ultimate decision as to whether or not to remove the President from office, nor does the Supreme Court have any jurisdiction to review the Senate's decision.

And, by the way, that's all that happens, should the President be found "guilty" in the Senate trial: he's removed from office. Period. He does not immediately go to prison/jail.

Neither President Clinton nor President Johnson were removed from office by the Senate (Johnson actually escaped that fate by only one vote; for more info on his impeachment and trial, see: http://www.pbs.org/wgbh/amex/grant/peopleevents/e_impeach.html).

If a sitting President were to be removed from office by the Senate, it would be up to state or federal officials (depending on what the alleged crime was that had caused the impeachment proceedings) to institute criminal proceedings afterward. A sitting President may not be tried for a crime while in office other than by impeachment proceedings, so if he is to go to jail for the alleged crime, he must be tried again by the judicial branch, after being removed from office in the impeachment proceedings.

a. ;)