It is well settled that customary law is a question of fact to be proved by evidence. See Section 14 of Evidence Law. Hence a party who alleges the existence of a particular custom must adduce sufficient evidence in support and to establish its existence to the satisfaction of the court. See Inyang v Ita (1929) 9 NLR 84. But there comes a time when by frequent litigation in the courts, a point of customary law has been sufficiently ruled upon, the courts will no longer require proof, and would be prepared to take judicial notice of it. See Angu v Attah, PC 74, 28, 43; Buraimo v Gbamgboye (1940) 15 NLR 139; Giwa v Erimolokun (1961) 1 All NLR 294, 1 SCNLR 337. The burden is on the defendants to establish the custom they rely upon for their defence. Balogun v Labiran (1988) 3 NWLR (Part 80) 66. Indeed only a single decision, sufficiently cogent and authoritative would be sufficient – Larinde v Afiko (1940) 6 WACA 108, but see Cole v Akinyele (1960) 5 FSC 84; (1960) SCNLR 192; Folami & others v Cole & others (1990) 2 NWLR (Part 133) 445.
– Karibe-Whyte JSC. Agbai v. Okogbue (1991) – SC 104/1989