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About 20 years after their introduction, and about 10 years after their first revision, the International Bar Association (“IBA”) recently published the new version of the IBA Rules on the Taking of Evidence in International Arbitration (“IBA Rules”).[1] The update aligns the IBA Rules with developments in the international arbitration practice and selectively clarifies its provisions. It furthermore responds to the “New Normal” of conducting arbitration hearings remotely. Fundamental changes, however, were not considered necessary.

The role of the IBA Rules in International Arbitration

The IBA Rules are intended to supplement the procedural rules in arbitration proceedings with regard to evidentiary issues. Most arbitration rules omit governing the taking of evidence in detail, but merely provide the arbitral tribunal with broad discretion. Against this background, the IBA Rules aim to provide guidance to the arbitral tribunal on conducting “an efficient, economical and fair process for the taking of evidence”.[2] Moreover, incorporating the IBA Rules into arbitration proceedings is meant to make the conduct of taking evidence more predictable for the parties. This again, may help to avoid subsequent proceedings regarding the due conduct of the arbitral process.[3]

Particularly when parties come from different legal cultures, their perception of how to take and assess evidence may vary largely. The idea behind the IBA Rules is to defuse this conflict. Their intention is to introduce an internationally accepted standard for the taking of evidence that incorporates elements of “both worlds”, the civil law and the common law.

Following their first publication in 1999, the IBA Rules became the predominant set of rules on conducting the taking of evidence in international arbitration. According to a 2016 report, about half of the surveyed arbitration proceedings referred to the IBA Rules.[4] Their application did, however, also raise concern and criticism. The most prominent “competitor”, the so-called “Prague Rules”,[5] are based on a more civil law-inspired approach. The Prague Rules have not yet been able to reach the same importance.

Content of the IBA Rules

The IBA Rules – or elements of them – can be included into arbitral proceedings in two ways: By choice of the parties or by determination of the arbitral tribunal. Even without an express incorporation, tribunals tend to refer to the IBA Rules when ruling on evidentiary questions, be it as soft law principle, as mere “guidance” or by way of analogy.

The IBA Rules deal with the admissibility and assessment of evidence as well as with the actual conduct of taking evidence. In principle, they grant broad discretion to the tribunal as to which evidence to allow and how to weigh it. Yet, the IBA Rules do provide a list of cases in which the arbitral tribunal shall – or may – exclude pieces of evidence. This is, inter alia, the case for irrelevant pieces of evidence or compelling instances of confidentiality and sensitivity.

The IBA Rules order the arbitral tribunal to conduct an early consultation with the parties to support an efficient and smooth process of taking evidence. For the procedure itself, the IBA Rules include detailed provisions on document production, on the testimony of witnesses and experts as well as the tribunal’s powers and on the conduct of hearings.

The rules on the production of documents from the opposing party are intended to be a compromise between different legal traditions. The IBA Rules allow only requests for documents and narrow categories of documents that are “relevant to the case and material to its outcome”.

Another notable feature is the section on party-appointed experts. The concept of party-appointed experts has its origins in the common law tradition. Nevertheless, it has become a widespread practice in all kinds of arbitration proceedings. Many arbitration laws and institutional rules presuppose the admissibility of this kind of evidence but it is the IBA Rules that set the standards for the composition and handling of their reports.

The 2020 update

The newly revised version is more of a very selective modernization of the IBA Rules than a general overhaul. The drafters have restrained from introducing fundamental modifications.

Article 2 – Consultation on Evidentiary Issues

The arbitral tribunal is encouraged to consult with the parties on questions of cybersecurity and data protection. Both topics have attracted more attention over the last years with the EU’s General Data Protection Regulation and initiatives such as the ICCA-NYC Bar CPR Protocol on Cybersecurity in International Arbitration.

Article 3 – Documents

The IBA Rules 2020 contain clarifications on the process of document production. The two most relevant are:

The party who has requested the production of documents has a right to reply if so directed by the arbitral tribunal, i.e. the party has the right to comment on the counterparty’s objections to the document production requests (Article 3.5).

Moreover, in accordance with current practice, documents that are produced voluntarily or because production is ordered by the arbitral tribunal need not be translated to the language of the proceedings. The documents only need to be translated if they are introduced to the record (Article 3.12(c)).

Articles 4 and 5 – Witnesses and Experts

The IBA Rules 2020 clarify that a second rebuttal Witness Statement or Expert Report may be submitted. However, such rebuttal Witness Statement or Expert Report is only admissible in order to respond to new matters that have not been previously presented in the arbitration or new factual developments (Articles 4.6 and 5.3).

Article 8 – Evidentiary Hearing

The most striking updates are related to remote hearings – an element that became tremendously relevant during the past year and will most probably play an eminent role in the conduct of international arbitration proceedings in the foreseeable future. Like several other players in the field, the IBA used the Covid-19 triggered “technological revolution” to update their rules in this regard.[6]

The previous version provided for in-person appearance to be the principle (with exceptions when submitting sound reasons). The revised Article 8 now grants the arbitral tribunal the power to hold evidentiary hearings remotely. Subsection 2 reads as follows:

“At the request of a Party or on its own motion, the Arbitral Tribunal may, after consultation with the Parties, order that the Evidentiary Hearing be conducted as a Remote Hearing. In that event, the Arbitral Tribunal shall consult with the Parties with a view to establishing a Remote Hearing protocol to conduct the Remote Hearing efficiently, fairly and, to the extent possible, without unintended interruptions. (…)”

Article 9 – Admissibility and Assessment of Evidence

The IBA Rules 2020 contain a new ground for excluding evidence, namely if the evidence was obtained illegally (Article 9.3). There was some debate and no consensus in the 2020 Review Task Force concerning this ground for excluding evidence.[7] The new IBA Rules 2020 provide discretion to the arbitral tribunal to rule on this issue taking into consideration various circumstances such as whether the party offering the evidence was involved in the illegality, whether the evidence has entered the public domain through public leaks or considerations of proportionality.


The scope of the changes in the new IBA Rules is not extensive. The update is nonetheless reasonable and important. Considering the widespread use of the IBA Rules, the number of effected arbitration proceedings will in any case be immense.


[2] cf. IBA Rules, Preamble 1.

[3] For an overview of annulment proceedings on the conduct of the arbitral process: see 2018 IBA Report (

[4] cf., p. 9.


[6] e.g. the ICC (; the LCIA (

[7] Commentary on the IBA Rules 2020.


Dr. Markus Altenkirch LL.M. is a member of Baker McKenzie's Dispute Resolution teams in Düsseldorf and London . Markus focuses on international arbitration and currently represents clients in ICC, DIS, LCIA, and HKIAC arbitrations. Markus primarily advises on Post-M&A as well as construction disputes. Moreover, Markus regularly advises on disputes in the Pharmaceutical industry. In 2021, Markus has started his own podcast series: #zukunft. Markus, and his colleague Lisa Reiser, interview leading arbitration practitioners and in-house lawyers on the future of international arbitration. Markus teaches at the University of Mainz and regularly publishes in the field of international arbitration. He is a contributor and editor for Global Arbitration News. Markus Altenkirch can be reached at and +49 211 311160 and +44 20 7919 1000.


Johannes Hagmann is a member of the Dispute Resolution team at Baker McKenzie in Frankfurt. He is currently a law clerk.