Which concept would best describe a situation where a party cannot deny a previous admission of a fact?

The situation described, where a party cannot deny a previous admission of a fact, is best captured by the concept of estoppel. Estoppel is a legal principle that prevents a party from arguing something contrary to a claim that they previously made, particularly when that previous claim has been relied upon by others. This means that if an individual has made a statement or taken a position that is acknowledged as true in a legal context, they cannot later contradict that statement because it would unfairly impact those who have relied on the initial admission.

In this context, estoppel serves to uphold the integrity of legal proceedings by ensuring that parties adhere to their prior representations, especially when such representations have influenced the actions of other parties. This principle fosters fairness and consistency, as it holds individuals accountable for their words and actions in previous dealings or discussions.

While other concepts, such as waiver, indemnity, and concealment, relate to different legal issues—waiver involves the relinquishment of a known right, indemnity pertains to compensation for loss or damage, and concealment involves the intentional hiding of information—they do not specifically address the denial of previously acknowledged facts as directly and effectively as estoppel does.