What legal principle prevents Cheryl from claiming the full $30,000 from her mother?

The legal principle that prevents Cheryl from claiming the full $30,000 from her mother is related to consideration. In contract law, consideration refers to something of value that is exchanged between parties in a contractual agreement. For a contract to be enforceable, there must typically be a bargain or exchange where each party provides something of value. In the case of gifts, which Cheryl may be attempting to claim, no consideration is exchanged. If Cheryl's mother intended to give the money as a gift rather than as a loan or in exchange for something else, then Cheryl has no legal basis for claiming repayment since gifts do not require consideration to be valid.

Understanding this principle highlights the distinction between a gift and a contractual obligation, which is crucial in scenarios involving family agreements or monetary exchanges. Other principles like promissory estoppel or unconscionability do not apply in this context since they deal with different aspects of legal obligations and fairness in contracts that are not present in the circumstances of a gift. Gift law also indicates that unconditional gifts do not create an enforceable obligation to return the gift, reinforcing Cheryl's inability to claim the full amount.