Final answer:
Estoppel is a legal doctrine that prevents a party from contradicting a fact they previously admitted or a position they have taken if doing so would harm another party who relied on that admission. It ensures consistency and fairness in legal proceedings, distinct from prior restraint and ex post facto laws.
Step-by-step explanation:
A legal doctrine that prevents the denial of a fact if the fact was admitted to be true by a previous action is known as estoppel. The principle of estoppel plays a critical role in ensuring consistency and fairness in legal proceedings. When a party has acknowledged a fact or embraced a certain legal position, estoppel can prevent that party from later contradicting that fact or asserting an inconsistent position if it would harm the party who relied on the original admission. This concept is aligned with the broader legal ideals of preventing injustice and avoiding abuse of legal process.
While estoppel helps in upholding justice, it is distinct from notions like prior restraint or ex post facto laws, which concern the timing and retroactivity of legal restrictions and laws. Estoppel, instead, is about the consistency of a party's representations and positions throughout a legal process. It is a powerful tool that upholds the integrity of judicial proceedings and ensures that parties cannot play fast and loose with the justice system.