¹ According to Article 155(1) of the Constitution, “If an Autonomous Community does not fulfil the obligations imposed upon it by the Constitution or other laws … the Government … may, following approval granted by an absolute majority of the Senate, take the measures necessary in order to compel the latter forcibly to meet said obligations … .” C.E., B.O.E. n. 311, Art. 155(1), Dec. 29, 1978 (Spain) [hereinafter Constitution], available at https://www.boe.es/legislacion/documentos/ConstitucionINGLES.pdf (in English). Only on one prior occasion had the central government invoked Article 155. It was in 1989 in relation to the refusal by the Canary Islands to comply with certain customs obligations arising from Spain's accession to the EU. An agreement was reached and that provision was never applied.

² These voices include heads of state and the president of the Commission of the Abellán, EU. Lucía, Merkel, Macron and May Show Support for Spain over Catalan Crisis , El País (Oct. 20, 2017)Google Scholar; Anderson, Emma, Putin Accuses EU of “Double Standards” on Catalonia and Kosovo , Politico (Oct. 19, 2017)Google Scholar; Casqueiro, Javier, Donald Trump: “It Would Be Foolish of Catalonia Not to Stay with Spain,” El País (Sept. 27, 2017)Google Scholar; Juncker Says Does Not Want Catalan Independence, Reuters (Oct. 13, 2017).

³ Prime Minister v. Parliament of Catalonia, STC 114/2017, Oct. 9, 2017 (ECLI:ES:TC:2017:114). All translations made in this work are by the author. On November 8, 2017, another important judgment was rendered by the Court on the legality of a Catalan “Law on Legal and Foundational Transition to a Republic” adopted on September 8, 2017. However, the references made therein to international and comparative constitutional law are more subtle. Therefore, this decision will not be addressed here (Prime Minister v. Parliament of Catalonia, STC 124/2017, Nov. 8, 2017 (ECLI:ES:TC:2017:124)).

⁴ For an overview of other decisions, see A. Garrido-Muñoz, Catalan Independence in the Spanish Constitutions and Courts, OUP Blog (Nov. 6, 2017).

⁵ Law on a Referendum on Self-Determination (Diari Oficial de la Generalitat the Catalunya 2017, 7449A) (Spain).

⁶ Prime Minister v. Parliament of Catalonia, supra note 3, para. I.1.

⁷ Id.

⁸ Id.

⁹ Id.

¹⁰ Id.

¹¹ Id.

¹² Id.

¹³ Id., with references to UN General Assembly Resolution 1514 and the judgment of the Supreme Court of Canada in Re the Secession of Quebec (see infra notes 20 and 26).

¹⁴ See below for more details.

¹⁵ The petition argued that the Catalan referendum was, inter alia, contrary to the following rules enshrined in the Code of Good Practice on Referendums: respect for the law and the Constitution and compliance with the rule of law (Rule III.1); absence of an impartial body in charge of organizing the referendum (Rule II.3.1); and absence of an effective system of appeals before an electoral commission or a court against the decisions of the organizing body (Rule II.3.3). See Code of Good Practice on Referendums, Mar. 19, 2007, Doc. CDL-AD(2007)008) (Spain). In support of these claims, the state attorney cited a letter dated June 2, 2017, sent by the president of the Venice Commission to the president of Catalonia. Therein, in response to a previous letter sent by the president of Catalonia informing of the celebration of the referendum, he underlined the need for such a referendum “to be carried out in full compliance with the Constitution and the applicable legislation.” Letter from Gianni Buquicchio, president of the Venice Commission, to Carles Puigdemont i Casamajó, president of the Catalan government, Réf J.Dem/307 – GB/ew, available at http://www.venice.coe.int/files/Letter%20to%20the%20President%20of%20the%20Government%20of%20Catalonia.pdf.

¹⁶ Prime Minister v. Parliament of Catalonia, supra note 3, para. I.5.

¹⁷ Id., para. II.2.A)

¹⁸ Id., para. II.2.A).b)

¹⁹ Id.

²⁰ Id., quoting Declaration on the Granting of Independence to Colonial Countries and Peoples, para. 6 (Resolution 1514 [XV], Dec. 14, 1960) (Spain).

²¹ Self-determination “shall not be construed as authorizing or encouraging any action that would dismember or impair, totally or in part, the territorial integrity or political unity of sovereign and independent States conducting themselves in compliance with the principle of equal rights and self-determination of peoples and thus possessed of a Government representing the whole people belonging to the territory without distinction of any kind.” Declaration on the Occasion of the Fiftieth Anniversary of the United Nations, para. 1, UN Doc. A/RES/50/6 (Oct. 24, 1995).

²² Consolidated versions available at Official Journal C 326, Oct. 26, 2012, 1–390.

²³ Prime Minister v. Parliament of Catalonia, supra note 3, para. II.3.

²⁴ Id., para. II.5.b, quoting 54 Senators v. Parliament of the Basque Country, STC 76/1988, Judgment on Constitutionality, para. II.3, Apr. 26, 1988 (ECLI:ES:TC:1988:76).

²⁵ See below for more details.

²⁶ Secession of Quebec, Re, Reference to Supreme Court, [1998] 2 SCR 217 (Can.).

²⁷ Antonio Cassese, Self-Determination of Peoples: A Legal Reappraisal 122–24, 328 (1995).

²⁸ In this regard, Article 2 of the 1978 Constitution “recognises and guarantees the right to autonomy of the nationalities and regions of which it is composed and the solidarity among them all.” Constitution, supra note 1, Art. 2. Catalonia was one of the few regions automatically entitled to autonomy from the very adoption of the Constitution. Other regions would only acquire such status at a later stage. This is due to what Article 143(1) of the Constitution describes as “historical, cultural and economic characteristics.” Id. Art. 143(1). Nowadays, among the seventeen regions in which Spain is divided, Catalonia has one of the most comprehensive legislative and executive apparatuses, with one important exception: national taxes, which only two historical regions (the Basque Country and Navarra) have the full power to collect and administer. Catalonia does have its own regional taxes. National taxes have caused bitter disagreements between the central and the Catalan government, even if Catalonia does have its own regional tax system. Such disagreements have not impeded, though, occasional support for the central government by Catalan nationalists in the Spanish Parliament in exchange for legislative and economic concessions.

²⁹ Cassese, supra note 27, 288–89,

³⁰ Final Act of the Conference on Security and Cooperation in Europe, at VIII, Aug. 1, 1975, 14 ILM 1293 (1975).

³¹ Secession of Quebec, Re, supra note 26, para. 151.

³² Texas v. White, 74 U.S. 700, 720, 725 (1868).

³³ BVerfG, Beschluss der 2, Kammer des Zweiten Senats vom 16, Dezember 2016 - 2 BvR 349/16, at http://www.bverfg.de/e/rk20161216_2bvr034916.html (Ger.).

³⁴ President of the Council of Ministers v. Region of Venetto, No. 118/2015, Apr. 29, 2015, para. 7.2, at https://www.cortecostituzionale.it/actionSchedaPronuncia.do?anno=2015&numero=118.

³⁵ “The continued existence and operation of the Canadian constitutional order could not be indifferent to a clear expression of a clear majority of Quebecers that they no longer wish to remain in Canada. The other provinces of the federal government would have no basis to deny the right of the government of Quebec to pursue secession, should a clear majority of the people of Quebec choose that goal, so long as in doing so, Quebec respects the rights of others… . There would be no conclusions predetermined by law on any issue.” Secession of Quebec, Re, supra note 26, para. 151.

³⁶ Marc Weller, Secession and Self-Determination in Western Europe: The Case of Catalonia, EJIL: Talk! (Oct. 18, 2017).

³⁷ See Accordance with International Law of the Unilateral Declaration of Independence in Respect of Kosovo, Advisory Opinion, 2010 ICJ Rep. 403, para. 109 (July 22).

³⁸ Crawford, James R., The Creation of States in International Law 651–64 (2d ed. 2006)Google Scholar

³⁹ The formal act of declaring independence and proclaiming a new constitution may be of special relevance in determining the date when a state comes into existence. In relation to the dissolution of the former Socialist Federal Republic of Yugoslavia, the International Court of Justice found that the new Federal Republic of Yugoslavia (predecessor of the current Republics of Serbia and Montenegro) came into existence on April 27, 1992, namely the day when its constitution was formally adopted and the new state proclaimed. It did so despite the fact that little—if nothing—was left of the old Yugoslav federation after the proclamation of Bosnia's independence on March 3, 1992 and the previous secession of the Republics of Slovenia and Croatia (see Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Croat. v. Serb.), Judgment, 2015 ICJ Rep. 52, para. 104 (Feb. 3)).

⁴⁰ See supra note 15.

⁴¹ In the elections held on Sept. 27, 2015 (deeply polarized over the celebration of the referendum and Catalonia's independence), pro-independence forces received 47.74% of votes. Due to the rules on geographical distribution of seats in the regional Parliament, this number nonetheless represented a majority of seats (72 over 135). Mr. Puigdemont's final appointment as president of the Catalan government was the result of post-election negotiations amongst pro-independence forces. He did not run as a candidate (Ashifa Kasam, Catalan Separatists Win Election and Claim It as Yes Vote for Breakaway, Guardian (Sept. 28, 2015)).

⁴² A different question is whether such a provision contains an obligation to respect Spain's territorial integrity addressed to EU institutions. See José Martín y Pérez de Nanclares, Legal Considerations Regarding a Hypothetical Unilateral Scenario of Independence by Catalonia: A Legally Unfeasible Political Scenario , 19 Span. Y.B. Int'l L. 52–54 (2015)Google Scholar.

⁴³ Although only applicable to breaches by EU member states, it is to be recalled that Article 7 of the Treaty on the European Union envisages a sanctioning mechanism for “serious and persistent” breaches of the values enshrined in TEU Article 2. Treaty on European Union, Arts. 2, 7, Feb. 7, 1992, 1992 OJ (C 191) [hereinafter TEU]. Such a mechanism has recently been activated in relation to Poland's reform of its judicial system. Commission Reasoned Proposal in Accordance with Article 7(1) of the Treaty on European Union Regarding the Rule of Law in Poland, Brussels, 20.12.2017 COM(2017) 835 final.

⁴⁴ According to TEU Article 2: “The Union is founded on the values of respect for … the rule of law … . These values are common to the Member States … .” TEU, supra note 43, Art. 2. See also Case 294/83, Parti écologiste “Les Verts” v. European Parliament, para. 23 (Eur. Ct. Justice Apr. 23, 1986) (“The European Economic Community is a Community based on the rule of law, inasmuch as neither its Member States nor its institutions can avoid a review of the question whether the measures adopted by them are in conformity with the basic constitutional charter, the Treaty.”).

⁴⁵ On the unconditional nature of EU law obligations, see Case C-265/95, Commission of the European Communities v. French Republic (Eur. Ct. Justice Dec. 9, 1997).

⁴⁶ TEU, supra note 43, Art. 4(3).

⁴⁷ Commission Reasoned Proposal, supra note 43, para. 2.

⁴⁸ A similar point has been made in a manifesto drafted by seven Spanish professors of public international law and signed by over four hundred international lawyers. See Statement on the Lack of Foundation on International Law of the Independence Referendum that Has Been Convened in Catalonia, Sept. 27, 2017, available at https://voicesfromspain.com/2017/09/27/statement-on-the-lack-of-foundation-on-international-law-of-the-independence-referendum-been-convened-in-catalonia.