RSBandBUpdate! episode 253 and the (brief) discussion of "finders, keepers" popped up.
Under common property law, there are three categories property may fall in to:
Lost- property found where the true owner most likely did not intend to place it, i.e. dropped wallet out of pocket when walking through airport
Mislaid- property found where the true owner most likely did intend to place it, i.e. using iPhone in cafe and forgot to pick it up again when he left
Abandoned- property that the owner intended to leave in that place
In most countries, abandoned property becomes becomes property of whoever found it, often with the exception of wreckages which become state property.
For mislaid property, it is deemed the responsibility of the the person who found it to surrender the item to the owner of the premises found upon. The premise's owner then takes up responsibility to hand back the property to the true owner
should he return. If the true owner does no return, it then becomes property of the premise's owner.
Finally, lost property. Depending on the country, the law may state either of the following. The law may state that lost property be treated as mislaid property, therefore the finder hands the item to the premise's owner, who then returns it to the true owner should he return, or keep it if he doesn't. The second option is for the law is to state that whoever finds the item has the right to claim possession over anyone
except the true owner. In areas where a lost property desk exists, it may or may not be law for the finder to hand it in, and if not, it is then up to the premise's owner to enforce the use of such service.