There's a certain park, in a certain city here in CA, that has produced a lot of silver over the years. It's a few hours away from me though, so I hit it whenever I'm passing through that part of the state. It's been detected since the late 1970s at least. I've detected it since the early 1980s. In all that time, just like coin-seeker78's situation, there's never been a problem, as far as anyone knew. I mean, sure, we had the "presence of mind" to go at low traffic times, be discreet when chasing the deeper ones, etc..
One time though, about 10 yrs. ago, a buddy and I were working the park. A lady cop comes up and launches in on us. You know, the typical song & dance not like coin-seeker's encounter here ("you can't do that", blah blah). Well as it turns out, my friend and I were getting ready to wrap it up for the day, so we gave her lip service, and left.
It just so happened, that just a month or two after that encounter, that I began to correspond with a hunter from that city, on a metal detecting forum, when we each recognized from each other's posts, that we were just a few hours from each other. In one of our communications, I told him of the booting we'd received just a month or two earlier, from the park in the center of his town. He emailed back that that was surprising, because he'd detected there, un-bothered, for a long time by then. And so too had his mentor who got him into the hobby, hunted there for many years. And as far as he knew, there was no rules or laws (specifically anyhow) saying you couldn't detect. Thus my information bothered him. It turned out, that his wife's family is "well connected" in that town (a relative on city council or something like that). So he told me he was going to have her "look into this" and "find out for sure" and "set that cop straight", blah blah blah. But I stopped him, and told him that maybe trying to go over some single cops head, was NOT the best idea. In other words, by parading this "pressing issue" in front of various park's dept officials, the city council, etc... might just be the avenue for them to make an official "no" or rule. I mean, let's face it, the hobby does have connotations, doh! And all that cop would have to say is "..... but they were tearing the place up" (even though that's not true), and guess who's going to win that debate? So rather than risk some real rule or policy coming into being, I told my new friend that "let's just give it a break". In the meantime, he figured that since no one ever said anything to him though, that he would continue to go, until told otherwise himself.
No one ever said "boo" to him, so eventually, we both forgot the matter, never "appealed" anything, etc...
About 6 or 8 months later, I was passing through that town again, and wanted to hit my favorite park. And since it was at an odd hour (after dusk, with little to no people, and at a different shift than the AM time I'd met the lady cop earlier that year), I hit the park again. No one said a thing. And ever since then, over the last 10 yrs, I've hit the park dozens of times, and never heard a peep again.
Now sure, I won't say that I didn't ... the first time or two ... keep a leery eye out for busy-bodies. And sure, it's easy for me to "give the park a break", since I only get through this town 2 or 3x p/year anyhow. Thus all this might be easy for me to say. And the town is big enough that the odds of any one cop having the same job, or even remembering you, is slim after a year or two. Perhaps this attitude won't work for a barney-fife 1-cop town where the station-house is right there over-looking the park. But I'm just trying to say, that a single cop or gardener saying "you can't do that", doesn't always make it law. Afterall, you have to figure this too: sometimes they're just answering a call, FROM SOMEONE ELSE, that they are duty-bound to please. When perhaps they themselves don't care. I've had that happen to, where a cop comes up ,and tells us point-blank "we had a call", and he ushers us on. Well to me, that only means he's "trying to keep the peace" and DOES NOT indicate this is a new law or policy. But sure, you give lip service right then, and don't simply return 30 min. later. I mean .... c'mon.