a. Customary Law in Ghana refers to the unwritten rules, practices, and traditions that govern the behavior of communities, derived from the long-established habits and usages of specific ethnic groups or localities. It is recognized as a key source of law under Article 11(2) of the 1992 Constitution of Ghana, which states that customary law consists of rules of law that, by custom, apply to particular communities in Ghana. In the banking context, customary law can influence matters such as land ownership used as collateral (e.g., stool lands or family properties), inheritance of accounts or assets, and even dispute resolutions in rural areas where banks operate branches. For instance, in lending practices, banks like GCB Bank must consider customary land tenure systems to avoid invalid securities, as seen in cases where family consent is required for pledging land.

In the given scenario, the noise-making ban during the Nunguase festival exemplifies customary law as a local tradition enforced by chiefs to maintain cultural and spiritual sanctity, potentially leading to sanctions like fines or social ostracism if violated.

b. Customary Law in Ghana is ascertained through a structured process to ensure its validity and applicability, primarily guided by judicial precedents and statutory provisions. The key methods include:

• Proof by Evidence from Experts or Witnesses: Customary law is proven in court by calling elders, chiefs, or knowledgeable community members as witnesses to testify on the existence and content of the custom. For example, in the case of Angu v. Attah (1916) PC, the Privy Council established that customs must be proven as facts unless they are notorious enough for judicial notice.
• Judicial Notice: If a custom is widely known and has been repeatedly upheld in courts, judges may take judicial notice without requiring proof. This is common for well-documented customs like the Akan matrilineal inheritance or Ga patrilineal systems, which banks encounter in succession matters for deceased customers’ accounts.
• Reference to Textbooks and Treatises: Courts and practitioners refer to authoritative writings by legal scholars, such as J.B. Danquah’s “Gold Coast Akan Laws and Customs” or modern compilations under the auspices of the National House of Chiefs, to ascertain customs.
• Statutory Recognition and Codification: Some customs are codified in statutes, like the Chieftaincy Act, 2008 (Act 759), which regulates chiefly customs, or the Intestate Succession Act, 1985 (PNDCL 111), which modifies traditional inheritance customs. The Courts Act, 1993 (Act 459) under Section 55 allows courts to apply customary law where applicable.
• Tests for Validity: To be ascertained as law, a custom must pass tests: it must be ancient (existing from time immemorial), reasonable, certain, and consistently observed as obligatory. It must not contradict statutory law or public policy, as per Article 26(2) of the 1992 Constitution, which prohibits customs that are injurious to health or dehumanizing.

In practical banking, ascertaining customary law is crucial during due diligence for loans secured by customary land, as per BoG’s guidelines on collateral. For example, during the 2017-2019 banking cleanup, failures to properly ascertain customary ownership contributed to non-performing loans in some collapsed banks like UT Bank. Banks often engage local solicitors or chiefs for verification to ensure compliance and avoid disputes.