Approaches to Evidence across Legal Cultures
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What is evidence? In summary, evidence is the material that a party provides to the arbitral tribunal in support of its factual assertions.
In domestic court proceedings, there are a variety of procedural rules regarding the admissibility of evidence, as well as rules regarding when and how evidence is to be submitted. In international arbitration, however, flexibility and party autonomy are prized qualities, and much is accordingly left to the discretion of the arbitral tribunal in cooperation with the parties. Evidentiary questions are generally governed by the law of the seat of arbitration, but arbitration laws are flexible with respect to evidential issues. Institutional rules also leave much to the discretion of the arbitral tribunal.
As is well known, the IBA Rules on the Taking of Evidence in International Arbitration (the IBA Rules) seek to fill this ‘intentional gap’ in international arbitration rules by providing general guidelines regarding evidential issues that have been widely accepted throughout the world. Nevertheless, as discussed below, there remain a number of issues on which arbitrators and counsel from different legal traditions can see matters quite differently.
This chapter provides a high-level introduction to issues concerning evidence as seen from an international perspective.
Evidence in international arbitration – the wider context
Having once been seen as a narrow western European field in which most protagonists knew each other socially, international arbitration has developed in the current century into a truly worldwide form of international dispute resolution.
In our view, it is important to remember this wider context when considering issues concerning evidence in international arbitration. It is sometimes suggested that there is an ‘international best practice’ by which diverse international procedures are being harmonised, and there is some considerable truth in this as is set out below. Nevertheless, local procedures and traditions still play a considerable role, depending on the parties, counsel and arbitrators involved.
In particular, there is a marked difference between those legal traditions (particularly, common law jurisdictions, but also Scandinavian countries) that strongly favour oral presentation of evidence and argument, and those legal traditions (including many civil law jurisdictions) that give precedence to written procedure and evidence.
The standard procedure in international arbitration places strong emphasis on written presentation, with detailed written submissions, written witness statements and expert reports, and often written post-hearing briefs. Yet the focus is still very much on the oral hearing, where the witnesses and experts are cross-examined.
We suggest that it is important to be aware that lawyers from different legal traditions will instinctively view the various parts of the international arbitration procedure differently. Thus, for example:
- Lawyers from civil law countries may expect to see a clear identification of the facts in dispute, and of the evidence relied upon to prove each of those facts. Common law lawyers, on the other hand, often prefer to use the evidence to tell their side of the story in a more discursive manner.
- Whereas common law lawyers prefer to rely on witnesses to present a narrative of what happened in the case, civil law lawyers prefer to rely on the underlying documents. In many civil law countries, witnesses play a rather minor role in civil court procedure.
- Lawyers from adversarial systems generally wish to use their own party-appointed experts, whereas lawyers from inquisitorial systems are accustomed to court-appointed or tribunal-appointed experts.
- Common law jurisdictions have far-reaching disclosure or discovery of documents, but civil law jurisdictions typically have only limited procedures for mandatory production of documents.
- Arbitrators from some civil law countries, such as Switzerland, tend to adopt rather more inquisitorial styles of questioning than would be done by arbitrators from countries that take a rather strict adversarial approach.
Set out below is an overview of standard procedure in international arbitration, followed by a discussion on a number of areas in which practices differ in different parts of the world.
Standard practice in international arbitration
There is a relatively standardised practice in international arbitration, which can be summarised as follows.
- The first step after the arbitral tribunal is constituted is for a case management conference to be held at which the arbitral tribunal and the parties seek to agree upon the detailed procedural rules for the arbitration (as generally set out in Procedural Order No. 1), as well as agreeing upon a procedural timetable. The case management conference is generally held virtually by videoconference.
- The parties prepare and submit two or three rounds of ‘memorial-style’ written submissions to which they attach the witness statements, expert reports and documentary evidence upon which they rely.
- A document production phase generally follows the first round of written submissions. The parties make specific requests for production of documents, usually in table format in the form of Redfern or Stern schedules. To the extent that the parties cannot agree, the arbitral tribunal rules upon the document requests.
- A further case management conference is often held prior to the main hearing.
- The main hearing lasts from one to two days up to one or two weeks, but rarely longer than that. The main hearing starts with oral opening statements, which are often limited to one or two hours each, followed by examination and cross-examination of witnesses and experts. The written witness statements are deemed to take the place of direct examination of witnesses, whereas experts often give oral presentations in which they summarise the contents of their expert reports. Most of the hearing is devoted to the cross-examination of witnesses and experts.
- Closing statements are often presented in writing in the form of post-hearing briefs, although (particularly in smaller cases) closing statements are sometimes presented orally.
- Short costs submissions are exchanged once the substantive proceedings have been completed.
- The arbitral tribunal is generally expected to issue its award within about three months of completion of the substantive proceedings.
This standard procedure places considerable importance on the written procedures. Most of the evidence – in the form of written witness statements, expert reports and documentary evidence – is presented in writing. Yet the focus often remains on the oral hearing and on the performance of witnesses and experts under cross-examination.
The fact that the oral hearing remains important is confirmed by the fact that it is rare for parties to agree to have a case resolved without a main hearing. It is commonly thought that parties have a right to a main hearing. A main hearing is generally held if one of the parties so requests, although in some cases the main hearing may be held online.
Nevertheless, at least in our experience, it is generally the contents of the relevant documents, supplemented by the contents of the written witness statements and expert reports, that determine the outcome of the case.
The IBA Rules versus the Prague Rules
It has become standard practice to have regard to the IBA Rules.
However, because of a perceived concern about the IBA Rules being based on common law procedures, the Rules on the Efficient Conduct of Proceedings in International Arbitration (the Prague Rules) were launched in December 2018. The Prague Rules aim to increase the efficiency of arbitral proceedings. The Prague Rules, inter alia:
- provide for the arbitral tribunal to take a proactive role;
- encourage the arbitral tribunal and the parties to avoid any form of document production;
- suggest that the arbitral tribunal and the parties should seek to resolve the dispute on a documents-only basis;
- provide for the arbitral tribunal to direct and control the examination of witnesses at any hearing; and
- include provisions for the arbitral tribunal to assist in amicable settlement of the case.
The Prague Rules provide interesting suggestions regarding various alternative procedural steps that arbitral tribunals and parties could agree upon. However, at least insofar as we have been able to ascertain, the Prague Rules have received only a limited uptake in practice. We suggest that one of the reasons for this is that there is no real need for alternative rules. As the IBA Rules themselves make clear, they do not need to be used slavishly and can be adapted to suit the particular requirements, and preferences, relevant to the case at hand.
It is relevant to note in this context that the aim of increasing efficiency is widespread in international arbitration (see, e.g., the case management techniques set out at Appendix IV of the International Chamber of Commerce (ICC) Arbitration Rules). It is therefore open to arbitrators in many cases to adopt some of the ideas that have been promoted in the Prague Rules, even when the Prague Rules themselves are not used. Thus, some civil law arbitrators may naturally seek to avoid any form of document production, or at least they may try to limit document production considerably. There is also sometimes a desire from civil law arbitrators to control the cross-examination process; in extreme cases, the arbitrators can end up taking over the questioning from the lawyers, but, less controversially, arbitrators from civil law jurisdictions often seek to limit or curtail the allotted time for cross-examination.
The issue of arbitrators assisting in amicable settlement is also particularly culturally sensitive. In Germany, it is common for arbitrators to be asked to give a preliminary view on various issues in the case, as a means of promoting settlement. However, in many other jurisdictions, this would generally be considered unacceptable.
As mentioned above, local procedures and traditions still play a considerable role in international arbitration, and so it is not surprising that variations can be seen in the standard procedure when considering international arbitration in different parts of the world.
Below, we seek to take account of possible regional variations and preferences in the following matters:
- witness evidence;
- expert evidence;
- documentary evidence;
- document production; and
- the burden and standard of proof.
As noted above, it is standard practice to prepare written witness statements for use in international arbitration. Article 4 of the IBA Rules provides some suggestions on how witness statements can be prepared.
However, it can be useful to bear in mind that regional variations can arise.
Party representatives as witnesses
There can be considerable scepticism in certain jurisdictions about party representatives acting as witnesses since party representatives are unlikely to give independent testimony. It should therefore be borne in mind that some civil law arbitrators may give rather less weight to the testimony of party representatives.
Length and style of witness statements
The length and style of witness statements can vary greatly, depending on how they are prepared. Common law lawyers, who are accustomed to preparing witness statements, often submit witness statements that are very detailed and run to many pages (commonly 50 or more). However, lawyers from jurisdictions in which witness statements are uncommon are more likely to submit much shorter witness statements, and these witness statements may have been prepared largely by the witnesses themselves.
How different styles of witness statements are perceived by the arbitral tribunal depends, of course, on the arbitrators.
Different procedures for filing witness statements
English lawyers may seek to have witness statements served simultaneously after written submissions have been filed, which is the usual practice in the English courts. The purpose of this procedure is to prevent one side from being able to read another side’s witness statements in advance of filing. However, even though the purpose of this procedure may be understood, this is likely to be perceived as a curious anomaly to international arbitration practitioners from outside England.
Preparing and coaching witnesses
Lawyers from continental Europe, as well as from England, are generally cautious about preparing or coaching witnesses, whereas the preparation of witnesses is generally expected in some other jurisdictions. It is important to be aware of these differences in approach as early as possible, and, if it seems likely to cause problems, this point should be discussed with the arbitral tribunal at an early case management conference.
Scandinavian lawyers prefer direct examination of witnesses, at least in part, and this in turn can result in requests for longer hearings.
Again, this difference of approach can cause difficulties unless it is discussed and planned for at a relatively early stage in the proceedings.
Different styles of cross-examination
Common law lawyers are taught specific techniques for cross-examination, and these techniques are often employed in international arbitration.
However, lawyers from other jurisdictions may have a different approach. Moreover, arbitrators from other jurisdictions may find certain styles of cross-examination to be objectionably aggressive.
Considerable care is needed to adapt the cross-examination to the needs of each particular case. In our experience, focus should be placed on the overall impression that is ultimately conveyed by the witness, with less emphasis being placed on counsel seeking to score detailed points. Whereas counsel sometimes try to get witnesses to admit that they are mistaken in various respects, arbitrators are often less concerned about minor errors that may, or may not, have been made by the witness. Thus, even if counsel manage to show that the witness is mistaken, the point may fall flat if the arbitrators nevertheless conclude that the witness has given a good overall impression.
Witness conferencing or ‘hot tubbing’ – where two or more witnesses or experts are heard together – can sometimes be very effective. However, considerable planning is needed for this procedure to work well, and there is considerable scope for disagreement as to how it should be carried out.
If witness conferencing is to be used, it is important that it is discussed and planned for in detail in good time before the hearing.
Concerns about witness reliability and memory
As has been recently publicised by the ICC, witnesses’ memory can be very unreliable and care needs to be taken to cater for this.
Counsel would be wise to take account of these concerns. Again, this is a matter that can usefully be raised at an early stage in the proceedings.
Generally regarding witness evidence
One of the most obvious cultural differences that arises in international arbitration concerns the length of witness evidence, and in particular the length of cross-examination. Counsel may sometimes plan to set aside a full day, or even longer, for the cross-examination of a key witness, but if the tribunal expects there to be only a limited number of specific questions, counsel’s strategy may need to be revised.
Similarly, if the arbitrators show that they consider the witness evidence to be rather unimportant, counsel should seek (as far as possible) to prove their case by reference to the documents.
Not all cases require expert evidence, but where experts are required, their evidence is often central to the case. Article 5 of the IBA Rules provides some suggestions for how expert reports can be prepared.
In practice, some lawyers are more experienced than others in dealing with experts. Those who are experienced will generally take care to ensure that the expert’s role is carefully defined and that the expert remains independent and impartial without seeming to become part of the counsel team.
However, some parties do not follow these guidelines. It is not uncommon for experts to develop and present the party’s case theory, particularly in specific fields such as construction where experts often have a prominent role. In our experience, it can be dangerous for experts to become part of the counsel team in this way since experts are less likely to be relied upon by the arbitrators when it is clear that they are not impartial.
It can be good practice to identify early on the issues that may require expert evidence, as is regularly seen in the English courts. However, this is somewhat uncommon in international arbitration.
Some arbitral tribunals prefer to appoint their own experts. The IBA Rules provide fairly detailed guidance on how tribunal-appointed experts should best be dealt with, but in our experience it is quite rare for parties to agree to these experts being appointed.
On the other hand, civil law arbitrators sometimes insist that they wish to appoint a tribunal-appointed expert. This is a particularly difficult cultural legal issue that needs to be handled carefully. One solution, by way of compromise, can be for the party-appointed experts to be jointly instructed to assist the arbitrators with certain tasks (e.g., the calculation of quantum).
Documentary evidence is generally submitted in the form of exhibits to written submissions.
Different formats for filing exhibits
International arbitration of 10 years ago involved multiple ‘bundles’ of hard copy documents, with a corresponding need for large amounts of documentation to be couriered around the globe. Thankfully, processes have improved and most arbitrations now deal for the most part with electronic documents.
Electronic documents present their own challenges. One particular issue concerns different levels of technical sophistication between lawyers from different jurisdictions. Some larger law firms are accustomed to using specialised software and presentation service providers, whereas other lawyers may have never encountered these systems.
Some arbitrators also have particular requirements with respect to electronic filing of documents, and it is wise for counsel to be prepared to be adaptable. Nothing annoys an arbitrator more than counsel’s failure to follow specific document filing instructions.
Different approaches to presentation of documentary evidence at hearings
As mentioned above, the standard procedure in international arbitration tends to focus on the hearing, but at the same time there is often rather little time at the hearing for the presentation of written documentation.
We suggest that, particularly in document-heavy cases, these issues need to be considered carefully at an early stage in the proceedings.
Issues concerning authenticity of documentary evidence
Many arbitral tribunals inform the parties that the authenticity of documentary evidence is assumed unless a party takes specific steps to challenge it.
In this new world where documents can be produced with the help of artificial intelligence, arbitral tribunals and parties may need to become more vigilant with respect to questions of authenticity.
Document production in international arbitration generally follows Article 3 of the IBA Rules. However, there are different views as to what is relevant and material, and there is very little guidance.
Lack of clarity concerning relevance and materiality
Article 3(3) of the IBA Rules states as follows:
Article 3: Documents
- A Request to Produce shall contain:
- a description of each requested Document sufficient to identify it, or
- a description in sufficient detail (including subject matter) of a narrow and specific requested category of Documents that are reasonably believed to exist; in the case of Documents maintained in electronic form, the requesting Party may, or the Arbitral Tribunal may order that it shall be required to, identify specific files, search terms, individuals or other means of searching for such Documents in an efficient and economical manner;
- a statement as to how the Documents requested are relevant to the case and material to its outcome; and
- a statement that the Documents requested are not in the possession, custody or control of the requesting Party or a statement of the reasons why it would be unreasonably burdensome for the requesting Party to produce such Documents, and
- a statement of the reasons why the requesting Party assumes the Documents requested are in the possession, custody or control of another Party.
The criteria ‘relevant to the case’ and ‘material to its outcome’ are not defined in the IBA Rules. The official commentary also provides little guidance beyond noting that the intention was to find ‘a balanced compromise between the broader view [concerning requests for production of documents] generally taken in common law countries and the narrower view generally held in civil law countries’, that Article 3.3 ‘is designed to prevent a broad “fishing expedition”’, and that ‘the relationship between the documents and the issues must be set forth in the request to produce with sufficient specificity so that the arbitral tribunal can understand the purpose for which the requesting party needs the requested documents’.
However, in the context of each particular case, it may be appropriate for the arbitral tribunal to provide clarity at a relatively early stage so that the parties can understand the basis upon which the arbitral tribunal will consider these issues. At the very least, the arbitral tribunal should ensure that it acts consistently in dealing with the various document requests made by each party – and in a large case with a considerable number of document requests, this requires diligence and care.
Some assistance can be obtained from the leading textbook on the IBA Rules. The authors note that there are two separate limbs to the test under Article 3.3(b) of the IBA Rules – ‘relevant to the case’ and ‘material to its outcome’ – both of which must be satisfied. Accordingly, it is good practice for parties to explain in their document production requests the relationship between a document request and the issue in the written submissions to which it is said to relate.
The main cultural legal sensitivity in this context concerns the extent to which a party can be ordered to hand over sensitive documents. For example, claimants from the United States may assume that they are entitled to obtain rather wide-ranging document production, whereas civil law respondents may assume that they should not have to disclose their trade secrets or other sensitive commercial documents. It is difficult to resolve such a culture clash.
Different approaches to e-discovery
E-discovery is a standard feature of US litigation, and it is apparently also common in domestic US arbitration for discovery of electronically stored information to be required.
However, wide-ranging discovery of documents is generally discouraged in international arbitration, and outside the United States it is relatively uncommon for e-discovery to be used in international arbitration cases.
Different views regarding legal privilege
It is also important to note in this context that rules concerning legal privilege vary widely across different jurisdictions. There is no standard guidance for dealing with privilege issues in international arbitration, and there is little guidance.
Against this background, parties and arbitral tribunals would be wise to identify any difficult issues concerning legal privilege at an early stage in the proceedings, and the arbitral tribunal should seek to adopt an even-handed approach that provides fairness in the circumstances of the particular case.
The burden and standard of proof
The important issues concerning the burden and standard of proof are largely unregulated in international arbitration.
The asserting party generally has the burden of proof with respect to an assertion. However, this simple rule does not necessarily resolve the complex issues that can arise concerning which party bears the burden of proof in determining the case as a whole. In some jurisdictions, it is sometimes suggested that the burden of proof should be placed on the party that has the best possibility of securing the evidence in question.
One preliminary consideration is whether the question of burden of proof is procedural or substantive, and accordingly which law applies – the law of the seat of arbitration or the substantive law. Although this question rarely arises in practice, issues could potentially arise in this context.
As regards the standard of proof, common law practitioners generally expect that proof needs to be shown in terms of a balance of probabilities, which is the usual requirement in civil cases. However, civil law lawyers may consider that something more is needed – in other words, that there is a requirement for the arbitrator to be convinced. Although it is sometimes suggested that, in practice, these standards are the same, in certain cases this issue could be determinative.
In our opinion, questions concerning the burden and standard of proof raise particularly sensitive cultural legal issues. Ultimately, counsel need to persuade the arbitrators, but if it is not even possible to agree upon these ground rules, then it is difficult to be sure of what is required. It is rare for these issues to be raised but we suggest that, in some cases, it could be very important for them to be discussed and agreed upon.
We conclude by noting that the international nature of the practice of international arbitration has a tendency to produce challenges and surprises whenever lawyers from different jurisdictions are involved, not least with respect to evidence.
Arbitrators and counsel would be wise to assume that every case is different, and that practices, views and expectations can differ widely.
Many of the possible issues that can arise are highlighted in the UNCITRAL Notes on Organizing Arbitral Proceedings.
The key point in each case is to remember the essential duties of the arbitral tribunal – to act fairly and impartially, and to give each party a reasonable opportunity to present its case. The arbitral tribunal and the parties should work together to identify and apply suitable procedures to resolve each case accordingly.
 James Hope is a partner and Marcus Eklund is a senior associate at Vinge.
 See the opening paragraph of the Commentary on the revised text of the 2020 IBA Rules on the Taking of Evidence in International Arbitration (the IBA Rules), which points out that the principal institutional and ad hoc rules in international arbitration ‘are purposely silent about how evidence should be gathered and presented in any arbitration pursuant to those rules’.
 See, e.g., English Arbitration Act 1996, Section 34(1): ‘It shall be for the tribunal to decide all procedural and evidential matters, subject to the right of the parties to agree any matter.’; French Decree No. 2011-48 of 13 January 2011, Article 1467: ‘The arbitral tribunal shall take all necessary steps concerning evidentiary and procedural matters, unless the parties authorize it to delegate such tasks to one of its members.’ (applied to international arbitration by Article 1506); Swiss Private International Law Act of 18 December 1987, as amended, Article 184(1): ‘The arbitral tribunal shall conduct the taking of evidence itself.’; and Swedish Arbitration Act of 1999, Section 25(1): ‘The parties shall supply the evidence.’
 See, e.g., International Chamber of Commerce (ICC) 2021 Arbitration Rules, Article 25(1): ‘The arbitral tribunal shall proceed within as short a time as possible to establish the facts of the case by all appropriate means.’; United Nations Commission on International Trade Law (UNCITRAL) Arbitration Rules 2021, Article 27(4): ‘The arbitral tribunal shall determine the admissibility, relevance, materiality and weight of the evidence offered.’; Stockholm Chamber of Commerce (SCC) Arbitration Rules 2023, Article 31(1): ‘The admissibility, relevance, materiality, and weight of evidence shall be for the Arbitral Tribunal to determine.’; and Swiss Rules of International Arbitration 2021, Article 26(1): ‘The arbitral tribunal shall determine the admissibility, relevance, materiality, and weight of the evidence, as well as the burden of proof.’
 Perhaps the best illustration of the worldwide nature of arbitration is the International Council for Commercial Arbitration (ICCA), which describes itself as a worldwide non-governmental organisation devoted to promoting the use and improving the processes of arbitration, conciliation and other forms of dispute resolution. The most recent ICCA Congress, which took place in Edinburgh in 2022, welcomed over 1,300 delegates from all over the world.
 See, e.g., Richard Garnett, ‘International arbitration law: progress towards harmonization’, Melbourne Journal of International Law (2022), Vol. 3, Issue 2. See also Robin Oldenstam and Kristoffer Löf, ‘Best practice in international arbitration’, Avtalt Prosess: Voldgift i Praksis (Scandinavian University Press, 2015).
 See also Nigel Blackaby, Constantine Partasides and Alan Redfern, Redfern and Hunter on International Arbitration (7th edition, Oxford University Press, 2022), sections 6.22–6.217.
 The Redfern schedule is a table in landscape format containing all the document requests made by a party, together with the responses to those document requests and the decisions of the arbitral tribunal with respect to each document request. See also Blackaby, Partasides and Redfern, op. cit., sections 6.98–6.105.
 The Stern schedule is similar to the Redfern schedule, except that it is set out in rows rather than columns and is generally in ‘portrait’ format. See also Blackaby, Partasides and Redfern, op. cit., section 6.103.
 See the ICCA Reports No. 10, 2022: ‘Does a right to a physical hearing exist in international arbitration?’. This report, which arose out of the need for hearings to be conducted online during the covid-19 pandemic, concluded that most jurisdictions permit arbitral tribunals to order online hearings. The report also noted that in most jurisdictions, with the notable exception of Switzerland, each party has a right to oppose a decision to conduct a documents-only arbitration, and, accordingly, in most jurisdictions, each party has a right to request that a hearing takes place (see p. 12 of the report).
 See, e.g., ICC 2021 Arbitration Rules, Article 26(1): ‘A hearing shall be held if any of the parties so requests or, failing such a request, if the arbitral tribunal on its own motion decides to hear the parties.’; UNCITRAL Arbitration Rules 2021, Article 17(3): ‘If at an appropriate stage of the proceedings any party so requests, the arbitral tribunal shall hold hearings for the presentation of evidence by witnesses, including expert witnesses, or for oral argument. In the absence of such a request, the arbitral tribunal shall decide whether to hold such hearings or whether the proceedings shall be conducted on the basis of documents and other materials.’; SCC Arbitration Rules 2023, Article 32(1): ‘A hearing shall be held if requested by a party, or if the Arbitral Tribunal deems it appropriate.’ But see the SCC Expedited Arbitration Rules 2023, Article 33(1): ‘A hearing shall be held only at the request of a party and if the Arbitrator considers the reasons for the request to be compelling.’ (emphasis added). By contrast, the Swiss Rules of International Arbitration 2021, Article 27(1) state that: ‘At any stage of the proceedings, the arbitral tribunal may hold a hearing for the presentation of evidence by witnesses or experts, or for oral argument. It shall issue directions in this respect after consulting with the parties.’ (emphasis added). Accordingly, the arbitral tribunal is not obliged to hold an oral hearing under the Swiss Rules. See Gabrielle Nater-Bass and Stefanie Pfisterer, ‘Chapter 3, Part II: Commentary on the Swiss Rules, Article 25 [Evidence and hearings, II]’, in Manuel Arroyo (ed), Arbitration in Switzerland: The Practitioner’s Guide (2nd edition, Kluwer, 2018), p. 687.
 It remains to be seen whether online hearings will become a ‘new normal’ in international arbitration following the covid-19 pandemic. In our experience, parties and counsel have been pleased to be able to meet in person again following the end of the pandemic, but online hearings provide considerable benefits in terms of cost, efficiency and environmental impact, and we expect that online hearings will continue to be used in suitable cases, particularly in smaller international arbitrations. Most modern arbitration rules expressly state that hearings can be held virtually; see, e.g., ICC 2021 Arbitration Rules, Article 26(1); UNCITRAL Arbitration Rules 2021, Article 28(4) regarding witnesses and experts being heard virtually; SCC Arbitration Rules 2023, Article 32(2); and Swiss Rules of International Arbitration 2021, Article 27(2). See also Article 8(2) of the IBA Rules.
 The preamble to the IBA Rules states that parties and arbitral tribunals ‘may adopt [the IBA Rules], in whole or in part, . . . or they may vary them or use them as guidelines in developing their own procedures’. It is stressed that the IBA Rules ‘are not intended to limit the flexibility that is inherent in, and an advantage of, international arbitration’ and that parties and arbitral tribunal ‘are free to adapt them to the particular circumstances of each arbitration’.
 See https://praguerules.com. The ‘Note from the Working Group’ at the beginning of the Prague Rules states: ‘One of the ways to increase the efficiency of arbitral proceedings is to encourage tribunals to take a more active role in managing the proceedings (as is traditionally done in many civil law countries). With this in mind [the] Working Group was formed.’
 The inquisitive nature of some of the provisions in the Prague Rules could also potentially cause due process issues in certain jurisdictions. For an analysis relating to Sweden, see James Hope and Nils Ivars, ‘Är Pragreglerna förenliga med svensk skiljemannarätt?’, SvJT (2019), 653–70.
 See footnote 13. The Prague Rules are also intended to be used in a similar manner.
 This point is addressed in Article 4(2) of the IBA Rules: ‘Any person may present evidence as a witness, including a Party or a Party’s Officer, employee or other representative.’
 For example, in Sweden, Article 6.3.1 of the 2020 Code of Professional Conduct for Members of the Swedish Bar Association states: ‘An Advocate must not exercise undue influence upon a witness or someone else testifying at Court. However, the Advocate is free to contact such person to obtain information about the testimony of that person even where the person is called to testify by the prosecutor or another opposing party.’ For an overview of different jurisdictions, see Gary B Born, ‘Witness Interviews and Preparation’, International Commercial Arbitration (3rd edition, Kluwer, 2022), §21.03[A][b].
 See, however, Article 4(3) of the IBA Rules: ‘It shall not be improper for a Party, its officers, employees, legal advisors or other representatives to interview its witnesses or potential witnesses and to discuss their prospective testimony with them.’ See also IBA Guidelines on Party Representation in International Arbitration, Guidelines 18–25.
 Whereas hearings of over two weeks are generally considered very uncommon in international arbitration, in Scandinavia it is relatively common for hearings in large arbitration cases to last up to three weeks or even longer.
 Typically, common law lawyers are taught to ask only leading questions on cross-examination, thus seeking ‘yes’ or ‘no’ answers. Common law lawyers also tend to expect to be given a generous amount of time for cross-examination.
 See, e.g., Robert H Smit, ‘Cross-examining witnesses before civil law arbitrators’, in Lawrence W Newman and Timothy G Nelson (eds), Take the Witness: Cross-Examination in International Arbitration (2nd edition, JurisNet, 2019).
 ‘ICC Arbitration and ADR Commission Report on the Accuracy of Fact Witness Memory in International Arbitration’, 30 November 2020.
 See Article 6 of the IBA Rules.
 In practice, arbitral tribunals are unlikely to proceed to appoint a tribunal-appointed expert if the parties jointly object. See also Section 25(1) of the Swedish Arbitration Act, which expressly prohibits a tribunal-appointed expert from being appointed where ‘both parties are opposed thereto’.
 Article 3(12) of the IBA Rules provides: ‘With respect to the form of submission or production of Documents, unless the Parties agree otherwise or, in the absence of such agreement, the Arbitral Tribunal decides otherwise: (a) copies of Documents shall conform to the originals and, at the request of the Arbitral Tribunal, any original shall be presented for inspection.’
 For a cautionary tale of the dangers of relying upon artificial intelligence, see Mata v. Avianca, Inc. 1:22-cv-01461 (S.D.N.Y.), Opinion and Order on Sanctions, 22 June 2023.
 Emphasis added.
 Commentary on the revised text of the 2020 IBA Rules, pp. 9–11.
 Roman Khodykin and Carol Mulcahy, with consultant editor Nicholas Fletcher, A Guide to the IBA Rules on the Taking of Evidence in International Arbitration (Oxford University Press, 2019).
 id., paragraphs (6.90)–(6.146).
 id., paragraph (6.99).
 See Shira A Scheindlin, ‘The intersection of e-discovery and arbitration’, Reuters, 20 July 2021, https://www.reuters.com/legal/legalindustry/intersection-e-discovery-arbitration-2021-07-20/.
 See, however, Article 9.4 of the IBA Rules, which states as follows: ‘In considering issues of legal impediment or privilege under Article 9.2(b), and insofar as permitted by any mandatory legal or ethical rules that are determined by it to be applicable, the Arbitral Tribunal may take into account: (a) any need to protect the confidentiality of a Document created or statement or oral communication made in connection with and for the purpose of providing or obtaining legal advice; (b) any need to protect the confidentiality of a Document created or statement or oral communication made in connection with and for the purpose of settlement negotiations; (c) the expectations of the Parties and their advisors at the time the legal impediment or privilege is said to have arisen; (d) any possible waiver of any applicable legal impediment or privilege by virtue of consent, earlier disclosure, affirmative use of the Document, statement, oral communication or advice contained therein, or otherwise; and (e) the need to maintain fairness and equality as between the Parties, particularly if they are subject to different legal or ethical rules.’
 See UNCITRAL Arbitration Rules 2021, Article 27(1): ‘Each party shall have the burden of proving the facts relied on to support its claim or defence.’
 For a detailed overview, see Richard Garnett, ‘Demystifying the Burden of Proof in International Arbitration’, in Franco Ferrari and Friedrich Rosenfeld (eds), Handbook of Evidence in International Commercial Arbitration: Key Concepts and Issues (Kluwer, 2022), pp. 67–86.
 This rule can sometimes apply in Sweden. See Lars Heuman, Bevisbörda och beviskrav i tvistemål (Norstedts Juridik, 2005), p. 41 et seq.
 For a clear overview of this complex subject, see Michael J Bond, ‘The standard of proof in international commercial arbitration’, The International Journal of Arbitration, Mediation and Dispute Management (2011), 77(3), 304–17.
 See, e.g., Article 22(4) of the 2021 ICC Arbitration Rules.