There are always unwritten, unspoken requirements.
The Constitution doesn’t mention a very real requirement that exists for holding office. That requirement is that the officeholder have legal capacity. The 25th Amendment does (in its third section) discuss this, but that was only ratified in 1967 (as a response to the assassination of President Kennedy in 1963).
The main utility of the 25th Amendment is in allowing to fill a vacancy in the office of Vice President. The added ability to deal with incapacity of the president is redundant—impeachment and removal already existed and fitted the need adequately, even if the idea of needing to impeach an incapacitated president seems a shade ugly.
But capacity is a real requirement, though only enforced politically (and thus rarely) in Congress as in the executive and the courts.
Like the Senate’s quorum rule, capacity is generally assumed to a fault, even when there is direct knowledge by those in government that an aged colleague may be failing. And in Congress the lack of capacity is generally overcome by the loyal and capable staffers who carry on with a governmental version of Weekend at Bernie’s.
But a short thought experiment will renounce any doubt that a constitutional capacity rule exists without ever being put to words. Let’s say a new pandemic occurred, or an attack with some novel nerve agent happened, and the result was mass-incapacity in Congress. Would the government honestly have to wait for the next general election to happen? With a bunch of demented or comatose legislators causing both chambers to sit idle, unable to even muster a quorum?
No. That dark day, it would take no time at all for everyone in the land to recognize that there is an obvious, unspoken rule that members must have capacity, and that a permanently incapacitated member forfeits their seat. A temporary loss of faculty might be survivable—litigation might occur if the matter ever came up, but not permanent incapacity.
In the case of a vacant mind, the laws of the state for filling the vacancy would be followed and the seat would be filled at the state’s described pace and in its chosen manner.
For those wondering, this all comes in light of the revelations regarding the fiction of Congressman Santos. While I do not know what will be done, I certainly think it is reasonable if a member is seen to have a complete lack of credibility to question their capacity to serve, and on that basis alone they should be expelled.
And the same should be true for a member too senile, as for a member otherwise lacking capacity permanently.
The case of temporary incapacity is harder to judge, and obviously it would depend on the circumstances, including how obvious it was that capacity could be recovered. The less likely it seemed, the better the case for removal and replacement. If such a member later regained their faculties, they could stand for election and, if the voters desired, be sent back to office at that later date.
There are likely some other de facto requirements, though it’s harder to judge if some are direct requirements or requirements of explicit requirements. For example, being a human is a likely requirement, but only humans are currently recognized as eligible to be citizens, and so it may be that the citizenship requirement would always be violated for non-humans seeking office.
Having a name may or may not fit that as well—the clerk has to call something on the role, and voters have to have a name to vote for. Being alive is certainly a requirement, or at least being animated enough to seem alive—to avoid becoming an estate. Officeholders have to be capable of at least some level of communication—enough to cast votes and to affirm their oath. That requirement may fit under capacity, however.
In any case, the capacity rule is something that should be given greater recognition.
