I am on the faculty committee of a very large interdisciplinary major. At last week's meeting we discussed hiring plans to replace someone whom we voted down in pre-tenure 3rd year review last year. S/he had a joint appointment and the other department voted to renew hir contract. Since we voted against renewal and the other department voted in favor, guess who gets to control the new hire?
We do--we are rewarded for being mean ("making the tough decisions"). Unlike when a faculty leaves or retires, if a department rejects someone at 3rd yr review or for tenure, that department retains that line and can fill it again the next year. At least that's how it works here.
So in essence, it is a way that the deans have of reassuring those departments that deny tenure that they won't be penalized. If a department votes in favor of tenure for someone, and then the college-wide committee votes to deny tenure, that department is not guaranteed that they will get to refill that soon-to-be-open position.
I hate this side of the tenure process. I hate the idea of being rewarded for firing someone.