I am French, so the US regulations about who can hold a gun where are complicated for me, I apologise if the question is obvious in the US.
YouTube brought me to a 2019 case (the TV News version and the bodycam version with more details) where a policeman in uniform (and with his service weapon) entered an IRS building for personal business.
He was then stopped and "chased" by a security guard because he did not want to remove his service weapon. The policeman was being asked whether he was on official duties (in which case I assume that the service weapon is fine, having all the right paperwork or situation), he said no and wanted to leave.
He was stopped by the security guard and finally, it is all the security guard's fault.
- Can a policeman enter a no-gun building with his service weapon while on duty, but for personal business?
- Can a policeman enter a no-gun building with his service weapon while not on duty (again, for personal business)?
- Can a security guard stop someone who entered the no-gun building by all reasonable means awaiting for police to intervene? (the rationale being that someone broke the law)