The study presents the impact of the historical origin of the making and application of law through a specific example. The regulation of nationality, a pivotal field of constitutional law, is considered a sovereign right of the Hungarian state which is exercised in line with Article G) of the Fundamental Law and Act No. LV of 1993 on Hungarian Citizenship. Hungarian naturalization practice, however, significantly changed in the wake of the amendment of the respective act: Hungarians living outside the borders have been entitled to preferential naturalization since 2011. This study aims to prove that this legislative action, which remarkably followed the designation of the day of the conclusion of the Trianon Peace Treaty as the Day of National Unity the previous year, was obviously influenced by historical considerations. The primary objective of preferential naturalization was to grant Hungarian nationality to persons of Hungarian origin whose ancestors had lost their Hungarian nationality in the aftermath of historical events involving the transfer of territories to neighbouring states. The study's point of departure is the Trianon Peace Treaty, the first major instrument to have a profound effect on the nationality of millions of Hungarians. The study explores the peculiar interpretation and application of treaty provisions relating to territorial changes and reveals the flaws in legal regulation which further contributed to the formation of a large community of Hungarians living outside the borders. Having surveyed the historical background, the analysis proceeds to examine the impact of historical traditions on the underlying motives and current domestic regulation of preferential naturalization. Evidence includes the broad scope of eligible persons, the wide range of documents accepted to prove descent, the verification of the required command of language, and the practical implementation of the procedure of naturalization. Research findings convincingly display the far-reaching effects of historical traditions on the regulation and practice of preferential naturalization in Hungary.