kinTN, I have heard of this tactic, that instead of asking some bureaucrat "can I metal detect?", that you instead phrase the question: "Are there are codes or laws here regarding metal detectors?" Or some such phrasing like that, that you would THINK puts the burden of proof on them, to PRODUCE and cite such a law (which there rarely is, at city levels, btw). Because as you correctly point out: If you just walk in asking them "can I detect at the park?", then that's a form of permission. Thus putting it up to their personal whims or mood, instead of asking for specific verbage in actual law/code. And then you are the susceptible to the old pschology of "no one cared .... TILL you asked" routine.
However, this can back-fire too. Even the way you phrase it for instance:
"Is there any city ord that makes metal detecting illegal on city property?"
Can be answered in the following way by the desk-bound clerk: "Yes there is. We have rules saying you can't dig and deface" Now notice you DIDN'T even say ANYTHING about "digging", right? Yet let's face it: that's the kneejerk reaction of some folks, and even though YOU know you'll leave no trace of your presence, yet.......... some busy-body is just going to pick the safe answer, with their own mental perceptions of what they *think* your hobby will do or entails.
And even to say "Is there any laws or rules that specifically mention metal detecting?" (thinking this means they'll have to cite a specific rule, that has THOSE specific words "metal detecting"), can also backfire. I heard of one guy carefully phrasing his question, so that the actual terms would be present in whatever answer he was to be given. And the lady at the desk said something like: "We would prefer you didn't". [As if he had just asked her permission]. And when the fellow objected and said "... but where is that written?", the conversation went downhill from there. Or an answer like this has often come back: "No there's nothing about metal detectors, but you can't dig" (again note: the questioner never mentioned digging!).
So my advice is DON'T ASK ANYONE. Instead, LOOK IT UP FOR YOURSELF. City codes, laws, and rules are always available somewhere for public viewing afterall. Either on the front desk at city hall, or on the city website, etc... You know, like: "No dogs allowed. No alcahol. Park closes at sunset", and so forth. If you see nothing saying anything about metal detectors, then presto, it must not be prohibited.
