Final answer:
The statement is true; legal detriment is the commitment, loss, or disadvantage a party takes on in a contract, which is a core part of the consideration necessary for a contract to be valid.
Step-by-step explanation:
The statement 'legal detriment means the obtaining by the promisor of that which he had no prior legal right to obtain' is True. Legal detriment refers to an obligation, loss, or disadvantage that a party agrees to in a contract, which can either be refraining from an action that one has a legal right to undertake or performing an action that one is not otherwise legally obligated to perform. This is a fundamental concept in contract law as it is related to the idea of consideration, which is the value that each party brings to a contract to make it binding. For instance, when a surgeon performs a surgery and expects payment, the payment serves as consideration for the surgeon's service, and the patient's legal duty to pay represents a legal detriment to the patient, as they must part with money they would otherwise retain.