Mfcttrf

I go to my local post office nearly every day to drop off packages for online purchases. A couple of years ago, I had a van full and it would have taken many trips to bring them inside. I asked a clerk if there was an easier way. The supervisor came out and told me to drive around back. I came around back to the fenced (not gated) employee area. No one met me. So, I walked in. He pointed me to the empty carts. I took one, filled it up and brought it back inside and asked him where to put the cart. I handed him my paperwork and left.

This was much easier for me. So, I started doing it every trip (4-6 times per week). The postal clerks all know me, see me and interact with me in the back room. I go to the far corner where the supervisor has his desk to hand him the paperwork. It seems like a decent arrangement. Makes it easier for me. No lines. And easier for them as I move the packages right to their sorting area.

Although it is clear to me that I am allowed there, I still feel a bit odd for being in the clearly labeled "employees only" area. I would think that at any time, they could revoke this permission, but do not since it is mutually beneficial.

I had some "Facebook lawyers" tell me that one day, I will get arrested. While I guess that could happen, I find it far more likely that if a postal police officer happened to be there one day, he'd question me, question the supervisor and either tell me that I cannot (or can) continue to access this area.

Does the long-standing policy of allowing my access grant me some-sort of (revocable) license to continue until told otherwise?

Trespassing requires that you be on someone else's property without their permission. The supervisor has explicitly given you permission, so it's not possible for you to trespass. You are correct that someone with the proper authority could revoke this permission at any time, at which point you would have to leave or be guilty of trespassing. The only way this situation could constitute trespassing is if they revoke your permission and you ignore them. You can't trespass somewhere that the property owner has allowed you to be and you observe the rules they have set (which may be implied) for you being there.

If they tell you to leave and you do not it is trespassing, but all you have to do is say OK and leave if they ask you to go. Anyone complaining about that is immature.