On hiring: it varies. If I have one position and I get a list with several applicants, than I just pick the best applicant and justify that decision. If I announce a position, get an applicant list and don't want to hire any of them, then yes I need to articulate why I think they are all unqualified.
At least with my agency the applicants go through a couple screenings before I get the list, and simply by being on the list that means HR thought they met minimum qualifications. So if I disagree on that, I definitely need to be able to articulate it.
A position that requires specific training (like a police academy) is worse from a hiring officer's standpoint. If they complete the training (academy or course) there is objective evidence that they met the minimum standards for the job. Not hiring someone that is objectively qualified if you have an open position is begging for a lawsuit. Not hiring a qualified protected class is begging to loose that lawsuit.
I don't know for sure about that department, but Law Enforcement in general is understaffed these days, so I would not be surprised if there were semi permanent open positions in many departments. In that situation if she rolled up with a shiny new academy graduation cert and applied for an open position they would pretty much have to hire her, at least on a probationary basis. And if she banged her training officer.......
FWIW, that's not limited to .gov jobs. I would bet money that any business big enough to have an HR has similar policies. They might not tell YOU why you didn't get hired, but there's a memo somewhere in HR detailing the hiring process and why a particular someone, or no one, was picked for a job just in case someone sues.
