Someone in The BBQ Pit or Politics & Elections posted that U.S. currency notes must be signed by the Treasurer and the Secretary of the Treasury, and that if the President replaces the signature of the Treasurer, then the bill would not be legal tender. A cite (the law) was posted. Unfortunately, I cannot find the post; so I’ll ask here: Is the poster’s assessment valid? Or are the signatures of the two Treasury officials just traditional?
According to this NPR interview, it’s legal. That was the first question.
INSKEEP: OK. So sit - so on this $10 bill, it’ll be on the left-hand side, is where it would be. OK. And is this legal to put a sitting president’s signature on the currency?
MCLAUGHLIN: Yes. So as far as the Treasury Department is concerned, the changing of signatures is actually quite routine. It happens anytime there’s a change of administration, and the administration appoints a new treasurer and a new Treasury secretary. So it’s not actually something that requires congressional approval or the passage of a law. The notes are updated with new appointees in every run, so it’s up to the Treasury Department to make that call when the new signatures go on the notes.
INSKEEP: OK. But…
MCLAUGHLIN: It’s just unprecedented, yeah.
Though it’s legal, it is a total break with a tradition going back 165 years.
That discussion does not distinguish between the case of changing the person who’s in the role of Treasurer or SecTreas, versus changing which roles sign the bills.
Yes the former happens quite routinely, certainly at every change of administration and sometimes more than once during an administration. However the latter is the topic at issue. So the cite is not a definitive answer at all.
As far as I can tell, the only law on the design of paper currency is 31 U.S. Code § 5114(b), which says nothing about signatures:
(b) United States currency has the inscription “In God We Trust” in a place the Secretary decides is appropriate. Only the portrait of a deceased individual may appear on United States currency and securities. The name of the individual shall be inscribed below the portrait.
Edit: There are some other minor provisions for the design of Federal Reserve notes (which is all of them nowadays):
Federal Reserve notes shall bear upon their faces a distinctive letter and serial number which shall be assigned by the Board of Governors of the Federal Reserve System to each Federal Reserve bank.
And:
Such notes shall be in form and tenor as directed by the Secretary of the Treasury under the provisions of this chapter and shall bear the distinctive numbers of the several Federal reserve banks through which they are issued.
Nothing about signatures there either.