Under undue influence, Juan should be able to set aside this contract between him and Sam. Undue influence arises when one party greatly influences another party which takes away their free will. These instances lack voluntary consent and are then voidable. This agreement greatly benefits Sam as Sam knows that without his help, Juan, who completely relies on Sam, will need to find another caretaker. Sams leverage of power in this case can be fully addressed under court and should have the contract set aside.

$4.$ Discuss fully whether either of the following contracts will be unenforceable on the ground that voluntary consent is lacking:

$($a$)$ Simmons finds a stone in his pasture that he believes to be quartz. Jenson, who also believes that the stone is quartz, contracts to purchase it for $$10.$ Just before delivery, the stone is discovered to be a diamond worth $$1,000.$

$($b$)$ Jacoby$$s barn is burned to the ground. He accuses Goldman$$s son of arson and threatens to have the prosecutor bring a criminal action unless Goldman agrees to pay him $$5,000.$ Goldman agrees to pay.