Nancy Pelosi has just been re-elected to the Speakership in the US House of Representatives, and will be serving her fourth and final term as Speaker there from now until, presumably, the third of January 2023. She was sworn in as Speaker, then administered the oath of office en masse to the Members-Elect. Given that Article 1, Section 2, Clause 5 of the Constitution states "The House of Representatives shall chuse [sic] their Speaker and other Officers; and shall have the sole Power of Impeachment," and that, being members-elect, they aren't yet members and thus aren't part of the House of Representatives, why is it they can on vote and elect the Speaker?
They are already Representatives before they take the oath.
The House of Representatives shall be composed of members chosen every second year by the people of the several states,
...the terms of Senators and Representatives [end] at noon on the 3d day of January, ... and the terms of their successors shall then begin.
There is nothing in Section 1 about "members-elect". There is nothing about oaths (except that senators take an oath when sitting in impeachment trials). So Members are already Members from noon on the third.
Article 6 requires:
The Senators and Representatives before mentioned, and the members of the several state legislatures, and all executive and judicial officers, both of the United States and of the several states, shall be bound by oath or affirmation, to support this Constitution
So they have to take an oath, though no particular form of words is defined. It is clear from precedent and practices over 200 years that members take the oath before they can begin any external matter, such as creating new laws.
The terms of the President and the Vice President shall end at noon on the 20th day of January, and the terms of Senators and Representatives at noon on the 3d day of January, of the years in which such terms would have ended if this article had not been ratified; and the terms of their successors shall then begin.
Yesterday was Jan 3, when Session 1 of the 117th Congress began, meaning that the new Representatives are now technically in office, minus the oath. Per the House website, the order of the new House is thus
Representatives usually take their oath during the first day of a new Congress, when the House organizes itself. After the Speaker is elected, the Member with the longest continuous service (the Dean of the House) administers the oath to the Speaker. This tradition originated in the British House of Commons, and has been the practice in the U.S. House since at least the 1820s (the Oath Act of 1789 did not mandate it). The Speaker, in turn, administers the oath to the rest of the Members en masse. The Speaker or Speaker Pro Tempore must swear in members who miss the mass swearing-in ceremony on the first day afterward; on rare occasions, the House has authorized other Members or local judges to swear-in absent Representatives.
Every representative (delegate or resident commissioner) having a certificate of election is a member unless and until they are expelled (or later excluded).
The Clerk of the House from the previous session assumes the chair and calls the House to order, a roll call is taken, then the Speaker is elected. The Speaker assumes the chair and continues the business of the House.
The detailed procedure used for the 116th Congress is available in the Congressional Record (PDF 218 pages) January 3, 2019.
RULE II Other Officers and Officials
- There shall be elected at the commencement of each Congress, to continue in office until their successors are chosen and qualified, a Clerk, a Sergeant-at-Arms, a Chief Administrative Officer, and a Chaplain. Each of these officers shall take an oath to support the Constitution of the United States, and for the true and faithful exercise of the duties of the office to the best of the knowledge and ability of the officer, and to keep the secrets of the House. Each of these officers shall appoint all of the employees of the department concerned provided for by law. The Clerk, Sergeant-at-Arms, and Chief Administrative Officer may be removed by the House or by the Speaker.
- (a) At the commencement of the first session of each Congress, the Clerk shall call the Members, Delegates, and Resident Commissioner to order and proceed to record their presence by States in alphabetical order, either by call of the roll or by use of the electronic voting system. Pending the election of a Speaker or Speaker pro tempore, and in the absence of a Member acting as Speaker pro tempore pursuant to clause 8(b)(3)(A) of rule I, the Clerk shall preserve order and decorum and decide all questions of order, subject to appeal by a Member, Delegate, or Resident Commissioner.