Doctrine of Covering the Field

The issue of covering the field is not much of any problem as regards Subsections (1), (2) & (3) of Section 4 of the Constitution. It is only in respect of Section 4 (4) & (5) that the issue of covering the field poses a problem. In respect of any matter in the concurrent list both the National Assembly and the State House of Assembly are empowered to make laws. However, whenever both the National Assembly and the State House of Assembly purport to make laws on any common item or matter in the concurrent Legislative List two situations may arise thus
I. If the Law enacted by the House of Assembly of a State is inconsistent with the Law validly enacted by the National Assembly, the law made by the National Assembly shall prevail, and the Law made by the House of Assembly shall, to the extent of inconsistency, be void. Section 4(5) of the Constitution is emphatic on this; and
II. Where the Laws made by both the National Assembly and the House of Assembly of a State with regard to the same issue or matter in the Concurrent Legislative List are not inconsistent, the Law made by the National Assembly enjoys superiority or paramountcy over the Law enacted on the subject by the House of Assembly of the State.
The decision of this Court in A. G, ABIA v. A. G, FEDERATION (2002) 6 NWLR (Pt. 763) 264 at 435 F puts it succinctly thus
The doctrine (of covering the field) however renders the paramount legislation predominant and the subordinate legislation remains inoperative so long as the paramount legislation remains operative. Where, of course, there is obvious inconsistency, the subordinate legislation is void.

The doctrine of covering the field is essentially that where the main, principal or superior law has covered a given field or area, any other subsidiary law made in that area or field cannot operate side by side with the main, principal or superior law. If the inferior law is inconsistent with the principal law, it has to be declared void to the extent of its inconsistency. But where it is consistent with the principal law, it has to be left in abeyance i.e. inoperative pending when the principal law may give way. See Saraki v Federal Republic of Nigeria (2016) LPELR – 40013 (SC), MPPP V INEC & Ors (2015) LPELR – 25706 (SC) AG Abia State & Ors v AG of the Federation(2002) LPELR 671 (SC), (2002) 6 NWLR (pt 763) 264. This Court, in Attorney General of Ogun State v Attorney General of Federation (1982) LPELR – 11 (SC), Per Fatayi – Williams, JSC (as he then was) held on this issue as follows:-
It is of course, settled law, based on the doctrine of covering the field with which I shall deal in more detail later, that if Parliament and a Regional Legislature are empowered to make laws, and a Regional legislature enacts an identical law on the same subject matter, the law made by Parliament shall prevail. That made by the Regional legislature shall become irrelevant and therefore impliedly repealed.