"When a plea of issue estoppel is raised by a defendant as in this case, it is to bar a party from re-litigating an issue conclusively decided in a previous suit in a later suit. See: Milad, Benue State v. O. P. Ulegede (2001) 10 SCNJ 43; (2001) 17 NWLR (Pt. 741) 194.

Estoppel is a rule that prevents a person to assert the contrary of a fact or state of things which he formally asserted by words or conduct. Put in another way, a person shall not be allowed to say one thing at one time and the opposite at another time. Estoppel is based on Equity and good conscience, the object being to prevent fraud and ensure justice between the parties by promoting transparency and good faith.

Mabamije & Otto [2016]1 M. J. S. C (Pt. III) [Po 49] Paras. B-C