Translation:Shulchan Aruch/Choshen Mishpat/224

Paragraph 1- Whichever party has the doubt occur in his possession has the burden of proof. How so? If one swapped a cow for a donkey, and the owner of the donkey pulled the cow but the owner of the cow did not pull the donkey and the donkey died, the owner of the donkey has to prove his donkey was alive at the time the cow was pulled. The same applies to anything similar. There are those who say that the owner of the cow has the burden of proof because given that he acquires the donkey wherever it is, it is in his possession and he has the burden of proof, similar to what is discussed shortly with respect to a butcher. If he cannot bring a proof, the seller would swear that he was not aware of these defects and he would be exempt. If Reuven swapped a horse for wine with Shimon, and Shimon pulled the horse and a gentile came and took the horse and said it was stolen from him, and Shimon wants to retain the wine in his possession, and Reuven admits the horse was stolen, it is a fraudulent sale and Shimon may retain what is in his possession. If Reuven does not admit it was stolen, however, we say the gentile is lying and Shimon must give the wine to Reuven.

Paragraph 2- If a needle was discovered in the thick wall of the second stomach and it created a hole straight through and a spot of blood was visible, it is evident that the animal was a treifah prior to its slaughter. Thus, if the mouth of the wound congealed, it is evident that the animal was a treifah for three days prior to its slaughter. If the mouth of the wound did not congeal, the facts are uncertain and the butcher must bring proof that the animal became a treifah prior to him purchasing it because the doubt arose in his property. If he cannot bring proof, he must pay the cost to the seller.