Political defection has become one of the most visible symptoms of institutional weakness in Nigeria's Fourth Republic. Because the Constitution of the Federal Republic of Nigeria 1999 (as amended) makes party sponsorship a precondition of contesting any elective office, and because the Supreme Court has repeatedly held that the electoral mandate belongs to the political party rather than to the individual candidate, the question of what happens when an office holder abandons the party that sponsored him ought, in principle, to be governed by a single coherent constitutional logic. It is not. Sections 68(1)(g) and 109(1)(g) subject legislators to a rule-and-proviso regime under which defection triggers automatic loss of seat unless it results from a division affecting the national structure of the party. No equivalent provision touches the President, Vice President, Governor, or Deputy Governor; a silence this article terms a constitutional vacuum. This article argues that this vacuum is not a principled design choice but an unaddressed gap in the 1999 Constitution, and that it is being systematically exploited by executive office holders in a manner the framers plainly did not contemplate, producing starkly unequal consequences for legislators and executive office holders who commit what is, in substance, the same constitutional wrong. Drawing on Amaechi v INEC, Abegunde v Ondo State House of Assembly, and AG Federation v Atiku Abubakar, the article traces the doctrinal foundations of legislative defection law, exposes the structural flaws in its enforcement, and demonstrates that the same mandate theory which justifies sanctioning legislators for defection applies with at least equal force to the executive. It concludes with proposals for constitutional and statutory reform to close the vacuum and equalize the consequences of defection across both arms of government.
 

Keywords: political defection, cross carpeting, Section 68(1)(g), Section 109(1)(g), freedom of association, executive immunity, party sponsorship, Nigerian constitutional law