Navigating International arbitration requires an understanding of its own procedural and legal vocabulary. Terms such as seat, lex arbitri, lex causae, jurisdiction, award and interim measures can appear repeatedly in arbitration proceedings, yet they do not always mean what their ordinary-language equivalents suggest. This glossary explains some of the most important terms used in international arbitration and shows how they fit into the arbitration process.

1. What is Arbitration?

Arbitration is a private dispute resolution process in which parties agree to submit a dispute to one or more arbitrators, who determine the dispute and issue a binding decision known as an arbitral award. The procedure is governed by the parties’ agreement, applicable arbitration rules and the relevant legal framework.

2. What is an Arbitration Agreement?

An arbitration agreement is the agreement by which parties consent to submit disputes to arbitration. It may appear as an arbitration clause within a contract or as a separate agreement concluded after a dispute has arisen. The existence and scope of the agreement are central to determining the tribunal’s jurisdiction.

3. What is an Arbitration Clause?

An arbitration clause is a contractual provision stating that specified disputes arising from the relationship between the parties will be referred to arbitration. The clause may also identify the applicable arbitration rules, seat, institution or other procedural matters.

4. What is Consent to Arbitration?

Consent is the legal foundation of arbitration. In commercial arbitration, consent usually comes from the parties’ arbitration agreement. In investment arbitration for instance, a State’s consent may be contained in an investment treaty, domestic investment legislation or a contract. The investor generally accepts that offer of arbitration by commencing proceedings in accordance with the applicable instrument.

5. What is the Seat of Arbitration?

The seat of arbitration, sometimes called the legal place of arbitration, is the juridical location of the arbitration. It does not necessarily mean the physical location where hearings take place. The seat connects the arbitration to the procedural law of a particular jurisdiction and may determine which courts have supervisory jurisdiction over the arbitration, including proceedings concerning the setting aside of an award.

6. What is Lex Arbitri?

Lex arbitri means the law governing the arbitration as a procedural legal process. It is closely connected to the seat of arbitration and may regulate matters such as the relationship between the tribunal and national courts, procedural requirements, interim measures and challenges to an award. The lex arbitri should not be confused with the substantive law governing the underlying dispute.

7. What is a place of hearing?

The place of hearing is the physical or virtual location where an arbitration hearing takes place. It may be different from the legal seat. An arbitration seated in one jurisdiction may therefore conduct hearings somewhere else without changing its legal seat.

8. What is an Arbitral Tribunal?

The arbitral tribunal is the decision-making body constituted to determine the dispute. It may consist of a sole arbitrator or, depending on the applicable agreement and rules, a panel of three or more arbitrators. The tribunal’s authority is derived from the parties’ consent and the applicable legal framework.

9. Who is an Arbitrator?

An arbitrator is an individual appointed to determine the dispute. Arbitrators are expected to meet applicable requirements concerning independence and impartiality and to disclose circumstances that may give rise to concerns about their ability to act independently. The qualifications and appointment process depend on the applicable arbitration agreement and rules.

10. Who is a Presiding Arbitrator?

The presiding arbitrator, sometimes called the chair or president of the tribunal, is the member who leads a multi-member arbitral tribunal. The precise responsibilities of the presiding arbitrator depend on the applicable rules and the tribunal’s procedural arrangements.

11. What is an Arbitral Institution?

An arbitral institution is an organisation that administers arbitrations under its institutional rules. Examples include the ICC International Court of Arbitration¹, the London Court of International Arbitration (LCIA)² and the Permanent Court of Arbitration.³ Institutional arbitration should be distinguished from ad hoc arbitration, where no arbitral institution administers the proceedings.

12. What is ad hoc Arbitration?

An ad hoc arbitration is an arbitration that is not administered by a permanent arbitral institution. The parties and tribunal organise the proceedings under the applicable arbitration rules and legal framework. The UNCITRAL Arbitration Rules are widely used for ad hoc proceedings, although they may also be used in administered arbitrations.

13. What are Applicable Arbitration Rules?

The arbitration rules provide the procedural framework for conducting the arbitration. They may regulate matters including the appointment of arbitrators, written submissions, evidence, hearings, interim measures, costs and the form and effect of awards. UNCITRAL, ICC, LCIA and International Centre for Settlement of Investment Disputes (ICSID),⁴ among others, have their own procedural frameworks.

14. What is Jurisdiction?

Jurisdiction concerns the tribunal’s legal authority to hear and determine the dispute. Questions of jurisdiction may include whether there is valid consent to arbitration, whether the parties fall within the relevant arbitration agreement or treaty, and whether the dispute falls within its scope.

15. What is the Principle of Kompetenz-Kompetenz?

Kompetenz-Kompetenz is the principle that an arbitral tribunal may determine questions concerning its own jurisdiction, subject to the applicable legal framework and judicial review where permitted. In investment arbitration, for example, the ICSID Convention expressly provides that the tribunal is the judge of its own competence.

16. What is Admissibility?

Admissibility concerns whether a claim should be heard or considered by the tribunal even where the tribunal has jurisdiction over the dispute. Jurisdiction asks whether the tribunal has authority; admissibility concerns whether a particular claim is properly before it.

17. What are Merits?

The merits concern the substantive issues in dispute. Once jurisdictional and other preliminary questions have been addressed, the tribunal may determine whether a party breached its legal obligations and what consequences follow.

18. What is Lex Causae

Lex causae refers to the law applicable to the substance or merits of the dispute. It is distinct from the lex arbitri, which governs the arbitration as a procedural process. The applicable substantive law may be selected by the parties or determined by the tribunal under the applicable arbitration framework. Under the ICSID Convention, for example, the tribunal applies the rules of law agreed by the parties and, absent such agreement, the applicable law specified by Article 42 (1).⁵

19. What is Procedural Law?

Procedural law governs how the arbitration is conducted. It may address matters such as tribunal constitution, court intervention, procedural fairness, evidence, hearings and challenges to awards. The procedural law is commonly associated with the law of the seat.

20. What is Substantive Law?

Substantive law governs the rights and obligations that form the subject matter of the dispute. It may be national law, international law, contractual law, treaty provisions or a combination of applicable legal rules.

21. What is a Notice of Arbitration or Request for Arbitration?

A Notice of Arbitration or Request for Arbitration is the document through which arbitration is formally commenced under the applicable rules. Terminology varies between arbitration regimes. The document generally identifies the parties, the dispute, the legal basis for arbitration and the relief sought.

22. What is a Statement of Claim?

The Statement of Claim sets out the claimant’s case. It normally identifies the relevant facts, legal grounds, evidence and relief sought.

23.What is a Statement of Defence?

The Statement of Defence sets out the respondent’s response to the claimant’s case. It may address factual allegations, legal arguments, jurisdictional objections, liability and the relief sought by the claimant.

24. What is a Counter Claim?

A counterclaim is a claim brought by the respondent against the claimant within the same arbitration. Its admissibility depends on the scope of the arbitration agreement and the applicable rules.

25.What are Pleadings?

Pleadings are the formal written submissions through which the parties present their respective cases. They may include statements of claim and defence, replies, rejoinders and submissions addressing jurisdiction or other preliminary matters.

26. What is Document Production?

Document production is the process through which a party may be required to produce documents relevant to issues in dispute. The scope and procedure vary significantly between arbitration regimes and may be determined by the tribunal’s procedural orders.

27. What is a Witness Statement?

A witness statement is written evidence provided by a factual witness. It generally sets out the witness’s knowledge of relevant events and may be used as the witness’s evidence-in-chief at the hearing.

28. What is Expert Advise?

Expert evidence is evidence from a person with specialised knowledge relevant to an issue in dispute. Experts may address matters such as valuation, economics, engineering, environmental impacts, accounting or other technical questions.

29. What are Interim Measures?

Interim measures are temporary measures intended to preserve rights, evidence or the effectiveness of the arbitration while proceedings are ongoing. Depending on the applicable rules and law, they may include orders concerning preservation of assets or evidence, security or other measures necessary to protect the arbitral process. UNCITRAL and ICSID frameworks contain provisions dealing with interim or provisional measures.

30. What is a Procedural Order?

A procedural order is an order issued by the tribunal concerning the conduct of the arbitration. It may establish the procedural timetable, hearing arrangements, written submissions, document production, confidentiality and other case-management matters.

31. What is Case Management?

A case management conference is a procedural meeting between the tribunal and the parties used to organise the arbitration. It may address the issues in dispute, procedural timetable, evidence, hearings and other matters necessary for an efficient proceeding.

32. What is the Hearing Stage?

The hearing is the stage at which the parties may present oral submissions and, where applicable, witnesses and experts may give evidence and be questioned. Hearings may be conducted in person, remotely or through a hybrid arrangement, depending on the applicable rules and tribunal’s directions.

33. What is the Closing of Proceedings Stage?

The closing of proceedings marks the point at which the tribunal considers that the parties have had a sufficient opportunity to present their cases. The tribunal will then proceed towards deliberation and the issuance of the award, subject to any applicable procedural rules.

34. What are Deliberations?

Deliberations are the tribunal’s private consideration of the evidence, submissions and legal issues before it. The tribunal then reaches its decision in accordance with the applicable legal framework and procedural rules.

35. What is an Arbitral Award?

An arbitral award is the tribunal’s formal decision determining matters submitted to arbitration. An award may determine jurisdiction, liability, damages, costs or other relief, depending on the circumstances of the case. Under the UNCITRAL Rules, awards are final and binding on the parties.\

36. What is a Final Award?

A final award is the award that brings the tribunal’s determination of the matters before it to an end. The terminology can vary between arbitration regimes. In ICSID Convention arbitration, for example, the final Award disposes of the entire case.

37. What is an Interim Award?

An interim award is an award dealing with particular issues before the entire dispute has been finally determined. Depending on the applicable rules, a tribunal may issue an award concerning issues such as jurisdiction or liability before determining damages. The treatment of interim awards varies between arbitration regimes.

38. What is an Award on Jurisdiction?

An award on jurisdiction determines whether the tribunal has jurisdiction to hear the dispute. Depending on the applicable framework, jurisdictional questions may be determined separately or together with the merits.

39. What is an Award on Liability?

An award on liability determines whether a party is legally responsible for the conduct alleged by the opposing party. In some proceedings, liability may be determined separately from the amount of damages.

40. What are damages?

Damages are monetary compensation awarded to remedy loss or injury established by the tribunal. In investment arbitration, damages may involve complex questions of valuation, causation, mitigation and interest.

41. What are Costs?

Costs may include arbitration fees, tribunal fees, institutional costs and the parties’ legal and other expenses. The allocation of costs is determined according to the applicable rules, agreement and circumstances of the case.

42. What is an Arbitral Tribunal?

An arbitral tribunal may award interest on amounts due, depending on the applicable law, agreement and circumstances. Interest may be calculated for periods before and/or after the award.

43. What is a dissenting opinion?

A dissenting opinion is a separate opinion by an arbitrator who disagrees with the tribunal’s majority decision, where the applicable rules permit such an opinion. A concurring opinion may similarly explain agreement with the result but disagreement with aspects of the reasoning.

44. What does Setting aside or Annulment mean?

Setting aside or annulment refers to a procedure through which a competent national court, or in the case of ICSID arbitration the applicable Convention mechanism, may review an award on specified grounds. It is not ordinarily an appeal allowing a court to reconsider the entire dispute on its merits. The grounds and procedure depend on the applicable arbitration regime.

45. What is the process of Recognition?

Recognition is the process through which a court gives legal effect to an arbitral award within its jurisdiction. Recognition and enforcement are related but conceptually distinct: recognition concerns the legal status or effect of the award, while enforcement concerns compelling compliance with it.

46. What is the Enforcement Process?

Enforcement is the process through which a successful party seeks to have an arbitral award given effect, including through national courts where the losing party has assets. The New York Convention provides a major international framework for recognition and enforcement of foreign arbitral awards.

47. What is the New York Convention?

The Convention on the Recognition and Enforcement of Foreign Arbitral Awards 1958, commonly called the New York Convention, is a central international treaty governing the recognition and enforcement of foreign arbitral awards. It also requires contracting States to recognise arbitration agreements subject to the Convention’s requirements.

48. What is a Competent Court?

A competent court is a national court with legal authority to exercise a particular function in relation to the arbitration or award. Depending on the issue, this may include the courts at the seat or courts in a jurisdiction where enforcement is sought.

49. What does Confidentiality mean in arbitration?

Confidentiality concerns restrictions on the disclosure or use of information relating to the arbitration. Its scope is not uniform across all arbitration regimes and may arise from the parties’ agreement, applicable institutional rules, procedural orders or national law. UNCITRAL’s Notes on Organizing Arbitral Proceedings specifically identify confidentiality as a matter that may require consideration during the organisation of proceedings.

50. What does Transparency Mean in Arbitration?

Transparency concerns the availability of information about an arbitration to persons outside the immediate proceedings. It is particularly significant in investor-State arbitration, where public interests may be implicated. Specific transparency requirements may apply under treaty provisions, applicable arbitration rules or instruments such as the UNCITRAL Rules on Transparency in Treaty-based Investor-State Arbitration.

51. What is the Investor-State Dispute Settlement(ISDS)?

Investor-State Dispute Settlement (ISDS) refers to mechanisms through which an investor may bring a dispute against a host State under an applicable investment treaty, investment law or other instrument providing consent to arbitration. Arbitration is one form of ISDS.

52. Who is an Investor?

An investor is the individual or legal entity that makes or owns an investment and seeks to rely on the applicable investment protection framework. Whether a claimant qualifies as an investor is determined by the relevant treaty, legislation or other legal instrument.

53. Who is a Host state?

The host State is the State in which the relevant investment is located. In investment arbitration, the host State may be the respondent to claims brought by a qualifying foreign investor.

54. What is an Investment?

An investment is the economic activity, asset or interest protected under the applicable investment instrument. The precise definition varies between treaties, domestic legislation and other sources of consent.

55. What is a Cooling Off Period?

A cooling-off period is a period specified in some investment treaties or contracts during which the parties are expected to attempt to resolve a dispute before arbitration can be commenced. Its legal effect depends on the wording and interpretation of the relevant instrument.

56. Who is an Amicus Curiae?

An amicus curiae is a non-party that seeks to provide the tribunal with submissions or information relevant to the dispute. In investment arbitration, amicus participation can be particularly relevant where proceedings raise issues of public interest. Whether such participation is permitted depends on the applicable rules and tribunal’s procedural decisions.

57. What does Ex aequo et bono refer to?

Ex aequo et bono refers to deciding a dispute according to considerations of fairness rather than strictly applying the ordinary rules of law. An arbitral tribunal generally requires express authorisation from the parties before deciding on this basis.

58. Who is an Amiable Compositeur?

An amiable compositeur is an arbitrator authorised to decide a dispute according to principles of fairness or equity rather than being strictly bound by the ordinary rules of law, where the applicable legal framework permits this approach and the parties have authorised it.

59. What is Bifurcation?

Bifurcation is the division of an arbitration into separate procedural phases. For example, a tribunal may determine jurisdiction or liability before proceeding to damages. Bifurcation may be used where separating issues could make the proceedings more efficient.

60. What does Finality Refer to?

Finality refers to the principle that an arbitral award is intended to bring the tribunal’s determination to an end, subject to the limited post-award remedies available under the applicable legal framework. Finality does not necessarily mean that an award is immediately enforced; recognition and enforcement may require separate proceedings.

1. https://iccwbo.org/dispute-resolution/dispute-resolution-services/icc-international-court-of-arbitration/ ↩︎
2. https://www.lcia.org/ ↩︎
3. https://pca-cpa.org/home/ ↩︎
4. https://icsid.worldbank.org/ ↩︎
5. Convention on the Settlement of Investment Disputes between States and Nationals of Other States (opened for signature 18 March 1965, entered into force 14 October 1966) 575 UNTS 159, art 42(1). ↩︎