Mountain -digger, If I understand where you're trying to go with this (correct me if I'm wrong), then I disagree.
"They" DO "have the authority" to interpret. Sure, maybe not in a judicial sense (ie.: it can be "over-turned" upon review by a judge). But none-the-less, the rank-&-file cops, and all other "duly appointed government employees" do in fact have some latitude
to apply the laws in the course of their jobs.
I ran into this once, where a city public works guy (not even a cop, not even a gardener) booted me from some city park long ago. When I studied the matter further, I confirmed to myself that there was nothing that specifically said "no metal detectors" in that location.
Later, after talking to a lawyer friend of mine about this, he told me that the
city person CAN INDEED boot me on ancillary things he morphs to apply. Ie.: alter, deface, remove, annoy, etc... And that it didn't need to be specific. So I asked my lawyer friend: "
Then how is that anything less than arbitrary, whimsical, and ripe for abuse?? I mean, what's to stop that same person from booting people that wear blue T-shirts, simply because he 'thinks they'll bother the spotted owls' ?"
The lawyer told me that this level of in-the-field
interpretation HAS to rest with cops,
and city personnel. They HAVE to be able interpret to a myriad of circumstances that might arise. That's why laws are often-time written vaguely in the first place. Eg.: laws that "forbid annoyances", for instance. Because it's simply impossible to write a law for every last conceivable thing that someone might do. And without the power to apply, everyone would forever more be debating semantics with cops in the field. No cop could ever get his job done, without people debating them over word definitions, etc...
Hence a cop or a gardener or councilman, etc... can indeed come up and boot you. Sure you can defy him, and ask for a ticket, to "have your day in court". But obviously, most of us don't have that time or energy.
By the way: none of this legal premise, in my mind, equates to:
"therefore I will go ask permission, and seek clarifications ahead of time". On the contrary: I will still help myself, till-told-otherwise. But just saying, don't think that various city persons can't boot you and I.
I will just do my best to not run into said city persons. Even if that means detecting at night