Vacant U.S. Senate seats are in the news lately. Obama, Biden, and Clinton are all leaving office; Illinois legislators are talking about passing a law to prevent Gov. Blagojevich from appointing Obama’s replacement; and if Ted Stevens had been re-elected, he might have been expelled, leaving a vacancy to be filled.

It all got me wondering why there’s no uniform method for filling a vacancy. Each state has its own law for replacing a senator; most states require the governor to appoint a replacement, but some states limit that power, requiring the replacement to be from the same party as the vacater and/or requiring the governor to choose from a short list. And some states don’t let the governor make the appointment at all, requiring a special election instead. This leads to lots of confusion; for example, many people thought that Sarah Palin could have appointed herself to replace Ted Stevens if he was expelled, but it turns out that Alaska requires a special election to fill a vacant seat.

So where did this craziness come from, especially given that the U.S. Supreme Court ruled in 1995 that states aren’t allowed to set term limits for their U.S. senators?

Well, I did some googling and it turns out that it comes from the Seventeenth Amendment. This is commonly known as the amendment that required U.S. senators to be elected by the people instead of being chosen by state legislatures. But the amendment’s second paragraph states:

When vacancies happen in the representation of any State in the Senate, the executive authority of each State shall issue writs of election to fill such vacancies: Provided, That the legislature of any State may empower the executive thereof to make temporary appointments until the people fill the vacancies by election as the legislature may direct.

So, although the people must eventually vote in special elections to fill Senate vacancies, state legislatures can empower the governor to fill those vacancies temporarily. Hence, state-by-state differences in how the process unfolds.

This has been another episode of “Answers to Questions You Didn’t Ask.”

(P.S. Here are all the state statutes and relevant federal statutes and constitutional clauses. Found here.)