nick-march, I read the link you provided, about this supposed NJ incident. My answer to you is, that all the times I've read any of the compiled lists that have done over the years (like this one:
Federation of Metal Detector & Archaeological Clubs Inc. ) is that those apply to state PARKS. Not simply all "state land". The reason I believe this is the case, is that is exactly how those lists were compiled, IN THE FIRST place: Someone merely asked at each of the state park's office's "what are your rules regarding metal detecting", and then compiled their list, from the results of those inquiries. For example: that is how Doc Grim compiled his book "Treasure Laws of the United States", when that book came out in the 1980s, is here merely zeroxed off 50 letters, and sent them to each state parks head offices, for their park's dept. And then when he got the 50 replies, he merely put them in alphabetic order, in his book. So as such, it in inherently applying to park lands, not simply all state land, everywhere. For example: there might have been a rule "parks close at sunset" afterall. But ... no .... no one would interpret that to mean you can't be on ANY state land elsewhere, after sunset (lest how would you drive on state roads after sunset, doh!).
So my answer is, there is varying *types* of state lands, that would have different rules of their usage. And the park's dept. being just one of them. Other types of land could be road right of ways, for example, which, yes, are state-owned (if it was a state road), but no, are not necessarily held to the same things as park land usage rules (ie.: pedestrians could walk along the sidewalk there, for example, after dark, as there is no "closing" time, for example).
So to answer to your link, I'd say the following things:
1) that there must have therefore, been an actual rule, on the "conservation land" he was on. So, yes, perhaps it was not NJ "park dept", land, but that doesn't mean that "conservation land" in NJ doesn't also have some sort of "rules" that covered this.
2) THAT IS UTTER NONSENSE to begin with, if that story is true. I mean, c'mon!! What are the odds of a "conservation officer" being in the middle of nowhere, who really cares about those things, or would do that? I mean, this reminds me of some stories you will no doubt find (if you sleuthed long enough and hard enough), of a motorist being pulled over, by an over-zealous cop, for nothing but a tail-light out. The over-zealous cop "roughs him up", arrests him, confiscates his car, etc.... for something as minor as a tail-light out. I mean, could it happen? Sure, I suppose. But is it "normal"? NO! of course not. Those type stories are the exception, not the rule. And so I'm certain that this NJ story is a BIG anomoly exception, and no, I highly doubt "conservation officers" are hiding around cellar holes in the backwoods of NJ waiting to arrest 71 yr. old men and confiscate, etc...
If you want to latch on to isolated cases like that, of someone who got roughed up for something as innocuous as that (where, even the article/link admits he was never shown any rule that he had broken), then I have some news for you: you might as well take up another hobby. Because, sure, if you ask long enough and hard enough, even I can show you rules, codes, laws, etc... that ...... given enough "morphing", could be made to apply to your hobby of detecting. Eg.: don't harm the earthworms, damage and destruction clauses, public nuisances clauses, cultural heritage clauses, etc.... I mean, the list is endless. If you ask enough people if you can pick your own nose, you will eventually find someone to tell you "no" afterall.
As to your question about artifacts and the state taking them, do you really think anyone is standing over you, as you dig each hole, with a calculator, to do the math of the dates of each coin you find (to determine 50 or 100 yrs. or whatever)? Even the fellow in your link simply handed the officer the target. I mean, think about it nick-mark: even down to city and county levels of govt. land (simple park sandboxes, school-yards, etc...) where no one's ever had a problem before: Picture this: you find an old coin worth $10,000 in the sandbox. You walk into city hall, and ask to speak to their head lawyer. You ask them:
"
Hi, I found this on your city property. It's 101 yrs. old, it's worth $10k. Is it ok if I keep it for my own fun and enjoyment to sell on ebay, or does it belong to the city, since it was found on city land, and thus maybe deserves to be in the city museum?"
What do you think they will say nick-march? OF COURSE they will say "no you can't have it". I mean, sure, if you want to start down that rabbit trail, you can never have anything you find, if you want to sleuth deep enough, long enough. Even lost & found laws that each state has, mandates that you turn in all items worth over $100 (or whatever threshold your state might have) to the police lost & found. Yet a simple look at any beach hunters finds forum, and you will see no shortage of people finding rings, all the time. Do you think they are all running down to the police dept. each time? Might there be a scary story now and then of someone who didn't? Sure, I suppose. But is it the exception? Yes, of course.