It is an open question whether the Vacanices Reform Act applies to situations where the person has been fired by the President. The specific language of the law is “dies, resigns, or is otherwise unable to perform the functions and duties of the office...”
Does being fired mean one is ‘unable to perform the functions and duties’? In one sense, obviously yes, but I think it’s plain to see how any lawyer worth their salt could make a compelling argument otherwise.
Considering how liberal the DC Circuit Court is, it almost certainly plays out like this: Trump fires Sessions, appoints Pruitt citing VRA. Dems run screaming to the court. Uber-liberal justice issues a Stay of some kind on Pruitt’s appointment leaving Rosenstein in charge. Delay, delay, hearing, delay, counter suit, counter motion - three months have passed with Rosenstein at the helm and Bob the Mule still running his dog-and-pony show.
Also, the appointment under the VRA can only last for 210 days, and the person so appointed is not eligible to be appointed to permanent Department head. So if Pruitt has personal ambitions to be AG then he’d likely advise Trump not to take this route. Can’t you just see the ridiculous trial over whether or not the 108 days after Pruitt’s appointment and his actual taking the reins at DOJ due to the court’s stay count against those 210 days?
Regardless
Only to those who hyper-analyze the "dies, resigns, or is otherwise unable" language in the statute. If what you say represents some point of real life contention (can;t use Vacancies Act when the position is vacant due to being fired), why isn't there a "Vacancies Act uproar" over replacing Tillerson with Pompeo?
-- Also, the appointment under the VRA can only last for 210 days, and the person so appointed is not eligible to be appointed to permanent Department head. --
That's on the Senate. The "210 day" value isn't "straight up." 5 USC 3346 anticipates contention versus Senate confirmation, and can start the 210 day clock when the Senate rejects a nomination.
-- and the person so appointed is not eligible to be appointed to permanent Department head. --
I believe that is false, but I'm open to citation of history, or statute, etc. If what you say is true, Pompeo's nomination to Secretary of State will be void right off the bat.