So I looked it up. The writers got it half right. The 25th Amendment of the Constitution says:
Section 4. Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office unless the Vice President and a majority of either the principal officers of the executive department or of such other body as Congress may by law provide, transmit within four days to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office. Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress, within twenty-one days after receipt of the latter written declaration, or, if Congress is not in session, within twenty-one days after Congress is required to assemble, determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office.
The Vice President and Cabinet meet, declare him incapacitated, and they prepare a written declaration. The Vice President under these circumstances becomes Acting President. He has the power of the Presidency but the President is still the President. The Constitution requires that the VP immediately assume the job duties once the Speaker of the House and the President pro tempore of the Senate get the declaration. He doesn’t have to be sworn in, and nobody has ever actually been sworn in under these circumstances, or where the President has voluntarily said he was going to be temporarily incapacitated (a different provision in Article 25). Remember, he was already sworn in as Vice President. (Maybe one of these days I’ll be able to use the word “she” in this context. Or is that too far off into science fiction?)
Presidents have voluntarily turned over authority three times when they were undergoing medical procedures. Interestingly, when Reagan was shot and underwent surgery, George H.W. Bush refused to convene with the Cabinet to declare him temporarily incapacitated. He apparently felt it would be akin to a coup.
The Presidential Succession Act of 1947 provides for what happens if neither the President of Vice President can serve. In that case, there’s a line of succession starting with the Speaker of the House. Whichever one in the line takes over has to step down from their office. They are then sworn in as Acting President. They still have to step down when the President is able to serve again.
I give props to the writers of The Event for getting it half right. They did have the Cabinet convene and declare the President incapacitated. I realize the swearing in was more dramatic, but it was just plain wrong. The President is still the President until he dies. It might have been more interesting to have had the good guys (who correctly suspect the VP had a hand in the poisoning) shoot down the idea of the swearing in and constantly remind the VP that he’s only Acting President.
I also think Article 25 provides some interesting potential plots if the writers want to keep the evil Vice President in office a little longer. He could say the President is still incapacitated and then Congress will have to decide.
If you actually look up the laws that apply to your story, sometimes you’ll get great ideas you never thought of (which is the whole purpose behind The Writer’s Guide to the Courtroom). Doing your research pays off. Try to get it right.