Well gee, if you really want to get technical, all us USA guys are probably already breaking several levels of laws, each time you/we find a ring, for example. Or if you find a coin that sell on ebay. Or all that clad that you roll up and take to the bank, etc....
Here's what I mean: any financial gains you make, are you reporting them on your income tax?

Or were you aware that if you find an item worth (varies state by state) over something like $500, that you must first turn it in to the police lost & found. If no one claims it in 30 days, only then can you keep it. And if it's worth over a certain threshold dollar amount (I don't have the law right in front of me), the police are required to run a "found" ad in the newspaper for a certain # of days. If no one turns up in the 30 days, then you can keep it AFTER you pay the price of that newspaper publication. But seriously, do any of us do this? (be honest). And does anything ever become of it?
I mean, if we all thought about it long enough, and hard enough, we'd all just stay at home in our own backyards, eh?

I'm betting what happened to the poor young lady in the link was a VERY rare case indeed. I mean, for pete's sake, she wasn't even an md'r!