As part of its electoral campaign based on fear and threats, the Spanish government insists that Catalonia would be automatically excluded from the European Union as soon as it became a sovereign state. The Rajoy government grounds its position on two articles of the EU Treaty. In the first place, article 4.2, which states that "the Union shall respect the essential functions of [the member states], including ensuring the territorial integrity of the State." In the second place, article 20, which states that "any person holding the nationality of a Member State shall be a citizen of the Union."
Article 20 of the Treaty is certainly irrelevant to the issue at hand. It develops an important principle when it states that European citizenship derives from and overlaps with the original state citizenship and that, therefore, the EU remains committed to protect the human rights of all its citizens (even against Member States if necessary). Yet, from reading this article we cannot conclude anything about the creation of a new state within the Union in the same way that we cannot draw any conclusions on the same issue just by looking at the European rules which allocate the number of representatives each Member State may have in the European Parliament.
At first sight, Article 4.2’s reference to the territorial integrity of each Member State seems to be written in order to protect the indivisibility of the Spanish nation-state. As a matter of fact, some Spanish publicists have attempted to connect it with the infamous Article 8 of the 1978 Spanish Constitution, which entrusts the army with the mission of defending the "territorial integrity" of Spain. And they have even concluded that the EU has agreed to become the ultimate and direct guarantee of its members’ territories. But such an interpretation of Article 4.2 would be absolutely superficial and wrong.
The principle of territorial integrity has had a long history in international law. In 1919 the foundational pact of the League of Nations formally recognized it (in Article 10). But the concept of territorial integrity only refers to the boundaries of existing states and it has little to do with the right to self-determination. As the International Court of Justice established in December 1986 while addressing a territorial dispute between Mali and Burkina Faso, the purpose of the principle of territorial integrity is to deter existing sovereign states from changing the borders they have in common. That is, it would only apply in a case of self-determination (such as, say, the Moroccan Sahara) if a neighboring state (such as Algeria or Mauritania) took advantage of the creation of an independent Sahrawi republic to change current national borders.
In 1975, the United States, the Soviet Union and all European countries (except Albania) signed the Helsinki Act on Security and Cooperation in Europe. The Act went much further than the EU Treaty. In addition to committing themselves "to respect the territorial integrity of each State participating" (point 4), the signatory states regarded “as inviolable all one another's frontiers as well as the frontiers of all States in Europe " (point 3). Yet, fifteen years after, when Slovenia split from Yugoslavia, the same countries that had signed the Helsinki Act recognized Slovenia within a few days.
Ms. Reding, Vice-President of the European Commission, summed up the legal (and political) state of the question perfectly in a statement made to the newspaper Diario de Sevilla on 30 September. Asked about a hypothetical automatic exclusion of Catalonia, the EU Vice-President responded bluntly that “the international law is silent” in that regard and that Spain had to solve their internal problems alone. She then added that she had complete trust “in the European mentality of the Catalans.” (By the way, Mr. García-Margallo just announced at the Congress of Deputies that Ms. Reding had sent a letter where she was recanting from her statements in Seville. The foreign minister should make the letter public since, even if Ms. Reding has now decided to defend a hypothetical common position of the Commission, the truth is that the latter has never deviated from applying a principle of strict neutrality to the Catalan question.)
In short, the EU Treaties cannot be used against the democratic will of a people. It is true that they do not regulate a hypothetical process of internal enlargement of the EU. Still, the absence of regulation never implies prohibition – as repeatedly pointed out by the International Court of Justice. From a democratic point of view (a position that the Spanish governments seems to have a lot of trouble adopting), the current situation resembles the case of Switzerland’s French-speaking Jura, whose population wanted to secede from the canton of Bern in 1977. Although the Swiss constitution did not foresee this possibility, the will of the Jura people eventually prevailed and the Jura canton “joined” the Swiss Confederation two years later. That historical case contains a straight lesson for the Catalan people. They should make their way peacefully, hold a referendum and then, backed the reason of the majority, proceed to negotiate the terms under which they want to continue in Europe.