> If not my family, then maybe I could go Robin Hood, steal from the rich and sell cheaply to the poor.

Note "for value". If the price is unrealistically cheap, the courts can point out that the buyer should have been suspicious.

> I can't imagine that it works that way. I can believe that as a buyer of stolen good without knowing they were stolen, you won't be punished. But you will still have to return the stuff.

You don't have to return it, it's yours now. The point is that the bona fide purchaser is not a criminal and acted in good faith. If, however, there is the slightest whiff of a hint of a suspicion, those bona fides collapse and title reverts to the original owner.

It is harder to prove bona fides than you might think. Got a great price? Not for value, test fails. Knew the seller? Not bona fides, test fails. Bought it from someone who has no history of selling those items? Possible notice, test fails. And so on.

Look, here's the thing. Lawyers and judges have been working on this system (the common law) for nearly a thousand years. For day-to-day stuff like property, the loopholes are well and truly closed and have been for hundreds of years.

That I was an inadequate law student and now am an inadequate explainer does not change the fact that the common law is pretty damn adequate at providing sensible legal protection for almost all imaginable transactions.

(IANAL, TINLA)

Another question: what happens if somebody steals my Porsche and sells it to somebody else, but I still have a set of car keys. One day I notice my Porsche parked on the curb, use my keys to enter it and drive away? Is it then a Schrödinger-Porsche that belongs to both me and the person who bought it off the thief?

What if I never even noticed it was stolen?

In fact, as the thief, why even bother with stealing? Why not just sell, say, houses on ebay that don't belong to me?

1. I'd expect that a cheap Porsche minus keys would not be seen as "without notice".

If you had multiple sets of keys and some were stolen, then by repossessing the you are potentially a thief if the intermediate buyer was bona fide.

2. Whether or not you noticed is irrelevant, the crime was committed and the Crown or the People will take an interest.

3. Selling things that you neither possess nor own is fraud.

(IANAL, TINLA)

Think about it this way:

A thief steals a widget from you and sells it to me for $x. I have no reason to suspect it was stolen.

The thief then absconds with the $x and spends it on consumable goods; even if caught, the cash can't be recovered from him.

I currently have the widget and have lost nothing; you're currently the thief's only victim. But if the court takes the widget from me and gives it to you, you're fully compensated, while I am now the victim, because my $x has effectively been stolen with no compensation.

In other words, there are two people who have been victimized by the thief, but all the court can do is re-assign victimhood to one party or the other, which, all things being equal, it should be indifferent to. Allowing the purchaser to keep the widget is basically the same as saying that they'll have no part in deciding who is to be the victim, and allowing circumstance itself to determine that.

But the thief himself is always responsible, and it's entirely appropriate to extract from him as much compensation for both victims as is possible.

This is why cars have pieces of paper called titles (which you are not supposed to keep in the car itself).

[in my state] a title is an abstract bundle of rights and the piece of paper is a certificate of title. Having the certificate makes it easier to attempt to transfer the title, but lost certificates can be recovered and fraudulent transactions can be unwound.

In addition to what jacques_chester has said, never forget the law is adjudicated by humans, not computers. If a judge thinks you've found a "loophole" there's no guarantee he's going to take that too kindly to that line of argument. Yes, we've all heard stories about loopholes that worked, but for every one that did there were a great deal more that did not.

Indeed, an entire tributary of modern law (Equity) arose because of the excessive formalism of the common law as it then was.

SO if I understand this correctly, by buying the coins at ridiculously low prices and the fact that in the post he said it was weird and he tried to take advantage of it. Would he not completely fail the test?

He doesn't know they are stolen. It could have been a legit attempt to panic the market by someone hoping to recover their losses plus some profit in the recovery. It's not illegal to ride along.

I don't know. I imagine there is a body of caselaw dealing with these rules in the context of financial instruments and currency trading that would give more detailed tests.