TLDR: Under what circumstances could one successfully sue to gain control of stolen bitcoin? If it depends on what proportion of an addresses unspent output consists of your stolen bitcoin then what may the limit be?
I previously asked here about cryptocurrency and theft, and the answer was that bitcoin, unlike money, is not a negotiable instrument and therefore remains the property of the original owner when a thief sells it to a third party.
I asked about managing this issue on bitcoin stackexchange, and the answer said:
Regarding the question of ownership of stolen coins, that's really only applicable if your withdrawal is being funded from a UTXO that comes directly from a deposit of the stolen bitcoin. If the exchange previously combined that coin with other "clean" coins into one large UTXO (example transaction), then no one specifically can be pinpointed as having received the stolen bitcoin.
There is no currently unredeemed output which contains 100% pure pizza coins. All the pizza coins have been diluted somewhat with other coins. The purest remaining are these 100 BTC which are 90.7276% pure pizza coin, and just 11 transactions separated from the pizza transaction.
And as an aside, he mentions stolen bitcoin:
Edit: I just found these 100% pure allinvain coins - undiluted after 24 hops from when 25k BTC was stolen from his computer.
Edit 2: I don't mean to imply that the allinvain coins haven't been thoroughly looted. They have touched 755,796 different addresses since being stolen and are currently sitting in 109,235 different addresses, including 8 from my own personal wallet. The exact same 8 as have pizza coins in them, it turns out.
Can we accurately legally say what is the situation regards claiming these "bitcoin"?
An example situation would be if Alice had some bitcoin in a wallet, and her computer was hacked and the bitcoin transferred to Anonymous Bobs wallet. He then created a transaction that contained X% of Alice's stolen bitcoin and 100-X% of legally acquired bitcoin and transferred that to Honest Charlie who publishes their wallet address. Is there a value of X that would allow Alice to successfully claim the coins from Charlie? 100%, 99%, 90%, 50%, 1%? Or any other property that would determine if such a case could succeed?