The approaches of different legal systems to treaty interpretation in the context of the International Agreement on Taxation and the protection of financial interests between the Kingdom of Spain and the United Kingdom of Great Britain and Northern Ireland regarding Gibraltar

Abstract

The article analyses the differences and similarities in the interpretation of the International Agreement on Taxation and Protection of Financial Interests between Spain and the United Kingdom with respect to Gibraltar. It highlights that, although both legal systems apply the 1969 Vienna Convention, there are different approaches: Gibraltar, influenced by English common law, prioritises the literal and functional interpretation of the terms, avoiding local technicalities; while Spain, from its civil-continental tradition, complements the literal interpretation with a systematic and teleological interpretation, considering the context, the purpose of the treaty and the primacy of EU law. The text illustrates how these differences generate uncertainty in key concepts such as "overnight stays", "sporadic absences" or the tax residence of entities and trusts. It concludes that the application of the same treaty in different legal systems can lead to divergent interpretations, underlining the need for cooperation and dialogue to ensure legal certainty.