I am wondering what would happen if an incumbent US President were to lose a presidential election, but refuse to accept the result and to concede defeat (even after any legitimate challenges and appeals have failed)? Thus, the incumbent President refuses to leave the White House.
Is there any precedent for such an event? Are there any established processes in place to deal with such a situation?
At 12:00 Noon on January 20, the incoming President would accede to power and would at that point be able to decide who is and is not allowed on the White House Complex. The former president at that point could be ordered to leave by the sitting president, and would be removed by the Secret Service if he refused (in reality they would probably try to find some way to remove him with the least public fanfare possible). Although former presidents are entitled to a Secret Service detail, that detail cannot protect them from lawful detainment or arrest.
I find it completely unthinkable that a President would acknowledge the electoral defeat and still refuse to leave. The much more thinkable scenario is that a President disputes the election results. There is a tradition in the United States that the defeated candidate "concedes" the election with a call to the winner.
(The question has been edited to answer this part.)
Imagine the concession does not happen.
Instead, both candidates claim victory. They send lawyers to challenge the count in many or most states. Elected, partisan state officials get into the fray. Isolated cases of vote fraud are documented in a more or less credible way. Conspiracy theories mushroom. To complicate things further, imagine that one Supreme Court judge has retired or became medically unfit, and that the remaining ones are deadlocked 4-4.
The result would be utter chaos and an unpredictable outcome.
One might guess that the incumbent has an advantage in such a scenario, but it also matters where the majority of the State governments and the Federal judges stand.
There is no precedent for a president refusing to leave in the United states. There are Presidential transition laws that have been amended fairly regularly. These laws grant newly elected presidents and their team office space and clearances. The General Services Administration is responsible for provisioning space for the newly elected president and transition team, they are separate from the executive branch so the president can't directly interfere with this process. The Oath of Office ceremony on January 20th is the start to the new presidency, at which time the previous president has no real authority, there is no requirement that the current president resign. The level of force used in evicting a reluctant president would likely be a call by the new president.
As for a scenario where a president actively tries to stop the inauguration of a new president, in theory no one would follow such orders, as their ultimate oath is to the constitution itself not the President. This is a grey area of not following unlawful orders, which is a common theoretical position, but hard to enforce in practice. An act of preventing a transition of power would likely rise to the level that most people required to prevent such a thing would be uncooperative, but that opinion relies on a lot of hypothetical situations.
Since the question assumes that the incumbent has lost, the talk of court challenges and the like is not relevant. If such a challenges were to succeed, the incumbent would be the winner.
Once Congress has finished with its 12th-amendment duties in determining the winner of the election, the result is decided. It is not necessary for defeated candidates to concede. Courts are generally unwilling to review political matters such as this.
If Congress determined that the incumbent president had lost the election, then, as a matter of law, that person would cease to be president at noon on January 20th. Refusing to leave the White House doesn't change that, and the new president's inability to enter the White House would not deprive him or her of the office of president.
By remaining in the White House without authorization, the outgoing president would be liable for conviction under 18 USC 1752 and a fine of up to $100,000 and/or imprisonment for up to one year (or a fine of up to $250,000 and imprisonment for up to 10 years if they resisted with weapons or if the resistance cause serious injury).
Is there any precedent for such an event? Are there any established processes in place to deal with such a situation?
As others have noted, there is certainly no precedent for this. I suppose the Secret Service probably has some procedure for this, but if they do it is probably, well, secret. In practice, as others have noted, the incoming president would likely decide what to do based on political considerations.
After January 20, following the election year, the president is no longer president. It's not a matter of choice, or concession. That's the law. Any 'orders' given by a former president after January 20 have no meaning.
The US military leaders are bound by law to uphold not the president, but the Constitution of the US. If the Constitution, or laws framed by it, state that a person is no longer president, then the military is required to ignore anything they say.
Generally speaking, presidents maintain the dignity of the office, and the stability of the nation, by being gracious in departure.
The only thing a president could do is subject themselves to the spectacle of being forcibly removed from the White House.
I am wondering what would happen if an incumbent US President lost a presidential election, but refused to accept the result and to concede defeat (and thus, refused to leave the White House)?
Like the other answers said, in the case of a completely unambiguous loss and the president alone contesting its validity, the Secret Service could be expected to remove the incumbent in time for the winner to move into the White House.
A few things they've left out:
In such a case, the president would obviously be experiencing massive psychological impairment. Everyone might try to just ride it out until the new administration, but the American presidency has become very imperial. There are dozens of things such a paranoid incumbent might order that would require his removal under the XXV Amendment.
It's standard fare for presidents to lose the election. 5 of the last 40 lost the popular vote (including 2 of the last 3), and another 5 won by less than 2% of the vote. Most police aren't federal and the Armed Forces swear their oaths to the Constitution, not to the offices. The Constitution says that the Electoral College is what matters, not the actual election itself. The usual thing for unhappy losers to do, though, is write think pieces and propose reforms, not try to hold onto the Oval Office chair for as long as possible.
It's possible that the incumbent—like the incumbents in many other countries—might have military allies that would make this more than a bout of insanity. Because of the oaths, that would likely require thinking that the opponent's term of office would do more harm to the Constitution than neglecting its terms would: Bernie probably isn't enough, but something like a one-man-one-vote-one-time Communist Party victory might. Someone who won the election but did so on a platform that essentially supports nixing the current Constitution in favor of something else. In that case, pretty much all bets are off: you might have them reinstitute fair elections fairly soon once they felt they would win them, you might end up with a decades-long military oligarchy like Turkey or Taiwan, or you might end up with a dictatorship testing the organizational skills of II Amendment enthusiasts.
I think the way the US Constitution works the presidential election that is exceedingly unlikely. The election of https://www.rbhayes.org/hayes/disputed-election-of-1876/ shows why.
Tilden won the popular vote and led in the electoral college, but 19 votes from three Republican-controlled states (Louisiana, Florida, and South Carolina) remained disputed. Oregon's count was also challenged. Allegations of widespread voter fraud forced Congress to set up a special electoral commission to determine the winner, composed of fifteen congressmen and Supreme Court justices. The commission finally announced their decision only two days before the inauguration. The vote was 8-7 along party lines to award the disputed electoral college votes to Hayes, making him the winner.
Basically it does not matter whether a presidential candidate concedes defeat or not. If Congress is on his or her side, then the candidate is not defeated - despite everything else. If Congress is against the candidate, then the candidate can not possibly win..
