Joe Biden was sworn in about ten minutes before Barack Obama. Does that mean that, officially, Biden was VP to George W. Bush for that time?
No. This and similar questions have been asked about a hundred different ways over the last few weeks. The switch happened at noon Eastern time earlier today. When and if the oath actually takes place is irrelevant.
Bonus! Even though Barack was actually sworn in at 12:04, Joe wasn’t the President for four minutes.
However, there were a couple of weeks in 2001 when we had the President married to a Senator.
nvm
Really? The constitution requires the oath, so it can hardly be irrelevant…
The oath is required to start giving orders, but the president becomes president at noon.
It’s completely irrelevant with respect to the time at which the terms begin and end, which is the question posed in the OP. Biden’s term could not possibly have begun before Bush’s term ended, under any circumstances; the Twentieth Amendment specifies that the beginning and end of Presidential and Vice Presidential terms is at noon.
Obviously, I can’t read today…
I agree that Bush’s term ended at noon, but how can it be said that Obama’s term began at exactly noon when he didn’t take the required oath until 12:04?
From Amendment 20 –
(bolding mine)
Seems pretty definite about when the term starts.
“…and the terms of their successors shall then begin,” Counselor Jokesterheimer! 
ETA: aw, nuts. 
Think of it this way: Obama became President at noon, but couldn’t give any orders until he took the oath.
Because, as the 20th amendment states, there can be no period between presidencies. As soon as someone ceases to be president the successor becomes president. Bush’s term ended at noon, therefore Obama’s term started at noon.
Isn’t implicit in this statement the fact that the “successors” qualify? By being a natural born citizen, at least age 35, 14 years a resident of the U.S., AND taking the required oath?
Say Obama wanted to be a PIA. Let’s say that he refused to take any oath, simply pointing to the 20th amendment as evidence that his term has begun and that he is now the President. Under your interpretation, would he be right?
Yes, He’d be right. He’d be wrong if he thinks he can do anything without the oath, however, or that it would go over well with the country.
So you are saying that a person can exist in a state where he IS the President of the United States, but unable to exercise any of the powers of the office?
That seems more convulted than saying that Atchison was President for a day or that Biden was President for four minutes…
Or how about: Since Obama/Roberts flubbed the oath, and Obama didn’t say word-for-word what is in the Constitution, he is not/cannot discharge the powers of the President of the United States?
The Constitution sets out three eligiblity conditions: being a natural-born citizen, having attained 35, being a resident for 14 years. Having taken the oath is not an eligibility condition.
Rather, it isn an obligation that must be discharged before entering on the execution of the office. Thus, after the beginning of his term but before taking the oath, the President is the President, but he ought not to act as the President.
The Constitution doesn’t say taht he cannot execute the office before taking the oath; it says that he must take the oath before executing the office.
In the same way, I must get a licence before I drive a car. But I can, in reality, drive a car without getting a licence. Were a new President to issue orders before taking the oath, he might be acting in breach of his constitutional obligations, but he is still acting, and the orders are still issued.
The Oath is not required to become President; it is required to exercise the powers of the Presidency. Picky difference, I grant. See Article II, Section 1, 8th paragraph of the original Constitution.