Like the title says what are the rules. If I miraculously got a private key to a wallet that had Bitcoin in it but was not mine originally then does that mean I now own the wallet like finders keepers and is there any legality issues with this in the usa,uk,canada,south america. Is this more of a morality should you or should you not.
I think that such a scenario is excluded, because I have never heard that someone could pick up the phrase the key to the wallet. I understand that this is what the post means. Nevertheless, if this happens, then the further actions depend solely on the moral views of the one who gained access to the wallet. I will say it bluntly - like 99 percent of people, I would immediately transfer this bitcoin to other wallets, most likely through services that you know very well about without me.
Another thing is if someone specifically hacks other people's wallets, spending effort and time on it, this is definitely the villain.