Treasure troves - finders keepers?

Imagine you were a builder that was hired to erect a shed on a farmer’s property, and while digging out the foundations, you uncover a collection of valuable items.  Who gets them: you as the finder, the farmer as the landowner, or the state/crown?

It should come as no surprise that this thorny question is the subject of laws governing what should happen, who will be the owner, and who should get rewarded.  In 1996 Britain introduced their Treasure Act (aka the Portable Antiquities Act) which essentially said that if the find is determined to be treasure and the owner cannot be found, it becomes property of the crown and the finder & landowner are rewarded (there’s a handy flyer on the subject that could be a good prop for a game).

That law replaced the Treasure Trove Law which had been part of English common law dating back to perhaps Edward the Confessor.  It was built on a few core principles:

• To be ‘treasure’ it had to be predominantly gold and silver; other metals, ceramics, stone and wood didn’t count, and gems were so rare they probably never imagined them to make a substantial proportion of the haul.
• The crucial question was whether the treasures were deliberately buried or lost by misadventure: if they were lost, they fell under the Law of Finders; if they were buried, the treasure becomes the property of the crown.

When a treasure trove was discovered, it was to be reported to the coroner who would then hold an inquest to determine what category applied to the find.  Failing to report a find was a crime punishable by fines or imprisonment; coroners were advised that such cases of concealed finds "may be well perceived where one liveth riotously and have done so of long time".  That is, people who formerly had little money who are now big spenders probably found a pile of treasure.

Scottish law remains very similar to the old English law, but is even stronger: all cases of “vacant goods” (ie things with no clear owner) belong to the crown.  American law was founded on the old English law, but has acquired the wrinkle that the finder, rather than the landowner or the state, is awarded possession (as long as they were acting on the property “in good faith”).

Sadly, common law doesn’t appear to say anything about treasures acquired through the ravages of dragons, giants, or goblin hordes, but I imagine that would count as “lost by misadventure”.  On the other hand, if the original owners could be determined, the treasures should be returned to them.  Likewise, any hauls taken from, say, a tomb would have been the possession of the crown. 

How would that play out in your game?  The characters just finished off the pirates and gathered up their booty; they head back to port and start spending, but get met by the merchants that the pirates were stealing from who want their stuff back.  Or they knock over the Tomb of Horrors with whatever they can carry, and the king’s agents turn up to demand they hand it over (being a deliberately buried hoard).