To understand fully the relevance of the first two clauses of the Fourteenth Amendment to secession, we need to examine the antebellum disputes about citizenship and sovereignty, the subject of Part II below. Issues about citizenship arose in the context of specific disputes about naturalization, expatriation, and the rights of freedmen, but they implicated conflicts over the seat of allegiance and the nature of the Union. Part III turns to the Reconstruction debates and shows how they reflect a fundamentally nationalistic view of citizenship. The Reconstruction Amendments to the Constitution were connected with a powerful vision of national citizenship and its implications for federal and state power. Under this vision, the national government had the first claim to the loyalty of citizens and in return was obligated to protect their rights as American citizens against state interference. An effort by a state to secede would directly imperil the status of its residents as American citizens, and both the federal government and the residents themselves had a duty to resist this interference with their constitutional rights. The two clauses in the Fourteenth Amendment dealing most directly with citizenship embody this vision.
Farber, Daniel A.
"The Fourteenth Amendment and the Unconstitutionality of Secession,"
Akron Law Review: Vol. 45
, Article 6.
Available at: http://ideaexchange.uakron.edu/akronlawreview/vol45/iss2/6