Anjouists have claimed in the past that because HRH the Count of Paris (de jure Henri VII of France) was born in Belgium, he should be considered a foreigner. Thus, if he is in the line of succession, so are the Spanish Bourbons.
There are many things wrong with this claim.
Firstly, the Prince’s birth in Belgium (Flanders) was done under duress. The illegitimate French Republic passed a Law of Exile in 1886, preventing French dynasts from living in France (though the Spanish Bourbons were not subject to the Law of Exile of 1886, showing they were not regarded as dynasts). This means the Prince’s birth abroad was not done by the choice of his family but out of force. Thus, it cannot be held against him.
Secondly, the laws of nationality (that is to say who was naturally French) had been changed. The Civil Code, often called the Napoleonic Code, was kept during the Bourbon Restoration by Louis XVIII and Charles X. The Civil Code stated that the children of Frenchmen born abroad were likewise French (jus sanguinis). In other words, the last legitimate government allowed for nationality by the principle of jus sanguinis. Thus, the Prince, under this law, was naturally French at birth.
[The law at the time of the Spanish Bourbons leaving for Spain, however, was based on jus soli. Thus, being born abroad by free choice and without lettres de naturalité, meant that the Spanish Bourbons were foreign.]
Thirdly, Flanders was generally exempted from the droit d’aubaine because Flanders had once been under the Royal Domain and the Flemish were considered “near foreign” rather than completely foreign. In other words, they were not considered étranger or aubain.
There is also the case of Ferdinand Philippe, who was born in Sicily. Like the above cases, this was one of exile. The kingdom had been overthrown, and then the republic had been overthrown by Napoleon. France had been politically unstable, thousands being killed in the revolution. Just six years before Ferdinand Philippe’s birth, Napoleon had the Duke of Enghien kidnapped from across the Rhine and “executed” (murdered). It was thus clear that Napoleon could not be trusted. Both Louis XVIII and Charles X remained in exile during this same period.