Person A owns a sheep and agrees to let Person B pretend that the sheep belongs to him, in order to win a prize. This was done under the pretence of the contract of sale between A and B. In other words A will pretend to sell the sheep to B so that B can use the sheep to win a prize - thereafter A and B will split the money. B presented a fake contract of sale and fake receipt which A signed. B later sell the sheep to C. When A later learns that his sheep was actually sold to C and is now seeking legal advice, and decides to use the rei vindication to recover his sheep.

C wants to know on what basis he can stop and prevent the rei vindication action.