Too Much (Or Not Enough) Spanish in International Arbitration?

Language is a form of identity that structures how we understand reality. Words reproduce norms, define boundaries, and determine, in arbitration, on whose hands the money ends. Poetry or contract, language is the civilised medium through which we express and resolve our grievances with one another. To choose dispute resolution by law is first to choose dispute resolution by words. Which language we use in international arbitration is far from a trivial question. Language both allows and limits how contracts are drafted, how international relationships are conducted, how obligations are interpreted and how disputes are thus resolved. Choosing the language of the arbitration entails practical, cultural and legal consequences. So, we must choose well.

Using Spanish in international arbitration has become common, driven by the rising number of arbitrations conducted in this language. It is reflected in practice and in the statistics of arbitral institutions, which confirm that Spanish has become one of the most used languages in international arbitration, often ranking second after English.

English need not be the default language of international arbitration. We, the three authors, have worked, both together and apart, in arbitrations in three different languages. We have some thoughts on the use of Spanish within international arbitration, on when to use it and what are the practical advantages of doing so.

I. Spanish as a Global Language and Its Relevance in International Arbitration

Spanish is quite an important language. Many people speak it and much business is done under it. It is the official language of 21 countries and the mother tongue of nearly 500 million people, with over 120 million more speakers worldwide. Behind those numbers sits the economy of Latin America and the Caribbean, which represents approximately 7.3% of global GDP. Spanish is an official language at the United Nations, the World Bank, International Centre for Settlement of Investment Disputes (“ICSID”), and the World Trade Organization. It is an authentic language of the United Nations Convention on Contracts for the International Sale of Goods (“CISG”). Few languages have better credentials.

Arbitration data follows. In Latin America, at least 76% of proceedings run in Spanish. Globally it is the second most used language in International Chamber of Commerce (“ICC”) awards. Many arbitral institutions administer cases in Spanish, across Latin America and beyond. The ICC and the International Centre for Dispute Resolution (“ICDR-AAA”) both can handle cases in Spanish, while the Centro Internacional e Iberoamericano de Arbitraje de Madrid ("CIIAM", formerly "CIAM-CIAR") reports that most of its proceedings are conducted in Spanish.

Investment arbitration leans on Spanish too. It is one of ICSID’s official languages, and many cases run exclusively in Spanish or on a bilingual basis. The Permanent Court of Arbitration (“PCA”) hears cases in Spanish too. On 27 May 2026, it held a Seminar on the Use of Spanish in International Arbitration Proceedings, gathering practitioners and arbitrators to present on its rise.

Institutions have promoted Spanish. The CIIAM and the Ibero-American Arbitration Club (“CEIA”) created the “Manifesto for the Use of Spanish in International Arbitration”. Organisations such as SEGIB and ALARB have strengthened Spanish through research, networks and practical tools. New trade agreements, including the EU-Mercosur framework, should generate disputes that will run in Spanish.

Organisations such as SEGIB, CEIA and ALARB have promoted Spanish through research, professional networks and practical tools, from arbitration dictionaries to training programmes. Together they strengthen Spanish as a working language in international legal practice. All seems good and dandy for Spanish. New trade agreements, the EU-Mercosur framework among them, should draw Spanish-speaking economies into contact with the rest of the world. Trade of that size generates disputes, many of which will run in Spanish.

II. Determining the Language of Arbitration

From knowing Spanish is popular, we do not yet get to know whether and where it is useful. One cannot derive an ought from an is. The most interesting question is normative: when should Spanish be the language of an arbitration?

Let us start with the arbitration clause. If a contract involves Spanish-speaking parties, jurisdictions or operations, the parties and their counsel should stop and ask whether English is indeed the right choice.

Where parties have not specified a language, tribunals must determine it from the circumstances. Where both parties are Spanish-speaking, Spanish aligns with the underlying relationship. It is easier to resolve in Spanish a dispute that emerged in Spanish. Years of communications and documentation in Spanish may amount to a tacit agreement on procedural language—it is hard to debate in one language the meaning of words written in another.

Four factors, taken together, answer the question. First, whether the parties themselves are Spanish-speaking and have dealt with each other in Spanish, regardless of the contract's drafting language. Second, whether the contract was negotiated, corresponded and performed in Spanish, even where its final text is in English. Third, whether the law governing the merits comes from a Spanish-speaking jurisdiction, so that the tribunal must ultimately read statutes, case law and doctrine in the original. Fourth, whether the seat is in a Spanish-speaking country, whose courts will support the arbitration and may later be asked to review or enforce the award. No single factor is decisive. Together, they locate the dispute's centre of gravity, and Spanish should follow it there.

Party autonomy is not absolute. Where parties agreed on English but negotiated and performed the contract in Spanish, arbitral practice describes this as facta concludentia: consistent conduct can evidence a tacit agreement on procedural language. Contractual choice should prevail when it reflects the parties' real intention, but yield when overtaken by how they actually dealt with each other.

When the applicable law comes from a Spanish-speaking jurisdiction, the tribunal can read statutes, case law and doctrine directly. This avoids double translation—first into English for the tribunal, then back as the reasoning is written up. A tribunal reading Spanish-language sources directly assesses how concepts have been construed locally, rather than through a translator's approximate rendering. Even where the contract is in English, if the governing law is Spanish-speaking, Spanish may still be the more efficient procedural language.

The seat plays its part too. If parties anticipate going before the local courts, those courts are more efficient in their own language. That is precisely why several jurisdictions have been setting up international courts, with foreign judges, to hear cases in languages other than the seat’s own.

The factors should be considered holistically. They point to the language at the “centre of gravity” of the dispute. The hard case is where the parties have agreed on, say, English, but everything else (the relationship, contract, documents, witnesses, seat…) points towards Spanish. Do tribunals have the flexibility, the power or even the duty to adapt the language of the proceedings when doing so would clearly be better for everyone?

III. The Advantages of Spanish

The language of arbitration shapes reasoning. In Spanish, the tribunal reads originals without distortions that translation smuggles in. Certain legal concepts carry no exact equivalent across traditions: “buena fe” is not fully coextensive with common law “good faith”, and “daños punitivos” sits uneasily with common law punitive damages, which most Ibero-American systems reject. Witness hedging in Spanish (“me parece que”, “entiendo que”) can read, once translated, as certainty the witness never claimed, colouring how a tribunal weighs credibility. A tribunal working from the original language avoids importing assumptions the source text never made, and assesses a witness's own words rather than an interpreter's reconstruction of them.

We will also remind everyone that arbitration can be expensive, and having to conduct one through translations, interpreters or even by reasoning through matters of interpretation across languages will not make it cheaper. AI-assisted translation is changing this calculus, but only partially. These tools now handle multilingual hearings competently and cut some of the logistical costs that used to justify a shared language almost by default. They remain imperfect, however, where a dispute turns on technical or culturally embedded legal concepts: legal language carries doctrinal traditions and interpretative assumptions that machine translation does not reliably capture, and a tribunal relying on AI output for a nuanced doctrinal argument risks reasoning from a paraphrase rather than the source. AI narrows the gap between languages. It does not close the case for choosing the language actually connected to the dispute.

Using Spanish also has a sociological upside. Spanish-speaking parties and counsel can work from their home language, improving the quality of advocacy and decision-making. Enforcement is smoother too. An award rendered in Spanish is one courts in Spanish-speaking jurisdictions can review and execute right away.

IV. Conclusion

Spanish has its place in international arbitration, English too. We ask only that the choice be taken seriously, not out of habit or inertia, but based on the circumstances: who are the parties, what is the contract, the governing law, the seat and the language of communications. Efficiency in a globalised world is not forcing everyone into a one-size-fits-all. The rise of Spanish reflects something larger: a more plural, inclusive and representative dispute resolution practice, better aligned with a multipolar world economy.