Does a President's mental incompetence invalidate his actions?

Question

Is a President required (or assumed) to be mentally competent in order to execute the powers of his office?

Can his action be undone retroactively if he is proved to be mentally incompetent at the time of his action?

Answer 1

Is a President required (or assumed) to be mentally competent in order to execute the powers of his office?

The President is conclusively presumed to be mentally competent until removed from office pursuant to Sections 3 and 4 the 25th Amendment to the U.S. Constitution. These sections say:

Section 3

Whenever the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that he is unable to discharge the powers and duties of his office, and until he transmits to them a written declaration to the contrary, such powers and duties shall be discharged by the Vice President as Acting President.

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.

Thus, the President is conclusively presumed to be competent until the President, or the Vice President supported by a majority of the cabinet, says otherwise in a written communication to Congress, and then is unable to act until the conditions for reinstating the President's authority have been met.

Exactly what constitutes "a majority of either the principal officers of the executive departments" at a time when not all cabinet positions have been filled, and when there are some cabinet positions that arguably don't count as one of "the principal officers of the executive departments" is an issue that has never been litigated or meaningfully clarified by Congress in this context.

On the other hand, if a subordinate of a mentally incapacitated President ignored an order of the President clearly rooted in this mental incapacity (e.g. "Nuke Toronto!"), and the President lacked the presence of mind to personally take action to try to enforce the order that was ignored, it is quite possible that nothing would happen to the person who ignored the order, which might end up not getting enforced in practice as a result of their inaction.

I recall from U.S. history classes long ago, although I don't recall the specifics, that the President's inner circle almost certainly did things like this in the waning days of, or during severe illnesses of, certain U.S. Presidents in the pre-modern period, even though the courts have never been required to rule on the propriety of this kind of conduct.

Can his action be undone retroactively if he is proved to be mentally incompetent at the time of his action?

No.

Interpretation of presidential pronouncements

This said, the courts interpret laws and other official pronouncements in a manner that seeks to reflect the intent of the person making those pronouncements.

For example, if the President, due to mental incapacity, says one thing, while clearly intending to say something else in light of the larger context of the statement, the courts might interpret the pronouncement of the President to reflect what the President meant, rather than what the President literally said.

For example, suppose that the President, as a result of mental incapacity, issued a pardon to "Mickey Mouse" at a time when the Disney Corporation was appealing a criminal judgment entered against it for tax fraud that he had railed against in previous speeches. The Presidential pardon might be interpreted by a court as a pardon intended to apply to the Disney Corporation, rather than to the fictional character whose earliest incarnations recently fell out of copyright into the public domain.

14th Amendment rational basis review

Also, since legislation and official actions of the President must meet a "rational basis test" to be constitutional, even if no constitutional rights or suspect classifications are at issue in the legislation, under the 14th Amendment's equal protection clause, a truly absurd order of the President might be invalidated based upon rational basis review under the equal protection clause of the 14th Amendment.

For example, if the President, as a result of mental incapacity, on Saint Patrick's Day ordered everyone in the U.S. military who was born on February 29 be required to wear an orange hat on the battlefield, and said it was because a leprechaun told him to give this order, the courts might invalidate that order on the basis of rational basis review under the equal protection clause of the 14th Amendment - since there is no rational basis to distinguish members of the military born on February 29 from members of the military who are not born on February 29.

Conclusion

But, in both of these examples, the fact that the President was mentally incompetent would not, itself, invalidate the Presidential order.