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M. Claudio Matute

Associé - Urzúa | Matute Abogados

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I. Definition and relevance


Cross-examination consists in interrogating the opposing party's witness who has already testified (i.e. direct examination). It may be followed by a re-direct examination.1 The scope of cross-examination is checking or discrediting the witness's testimony, knowledge, or credibility.


The origins of cross-examination can be traced back at least as far as ancient Rome.2 But in modern times, cross-examination came to be the main characteristic of the common law system. When the jury trial appeared as it is known today, also common law cases appeared to use cross examination to highlight when witnesses were not making true and reliable statements.3 A good example of the relevance of cross-examination in common law jurisdictions are the Federal Rules of Evidence that governs the introduction of evidence at civil and criminal trials in United States federal courts.4

II. Purpose of cross-examination


In general, the purpose of cross-examination is discrediting a witness or expert's credibility. International arbitral tribunals have sustained that the evidence of a witness who has been cross-examined may carry greater weight than the evidence of a witness who has not since it is a "powerful tool for getting at the truth. The value of this method of ascertaining the truth lies in the personal contact between the witness, who has no idea of what questions may be asked him, and the personality of the advocate who puts the questions to him."5


In addition, cross-examination complements the witness statement with information that has not been provided, allows to amend vagueness or falsehood in the declaration, to check facts are set in their proper contexts, and to reveal contradictions.6


Moreover, cross-examination has a persuasive function, giving counsel a chance, through the choice of questions, to focus the arbitral tribunal's attention on relevant issues of the case, as well as to events or key evidence to support that party's case.7 One of the best tools to be rhetorical is using leading questions,8 a type of questioning in that the form of the question suggests the answer. The tribunal will exercise discretion as to the probative weight to give to a cross-examination as opposed to written evidence,9 and may draw adverse inferences in case the witness is not available for cross-examination.10


Nevertheless, in international arbitration these rhetorical advantages might involve higher information and credibility risks than in jurisdictions where witness statements do not substitute direct oral testimony. Calling a witness for cross-examination turns a name on a statement into a person more likely to be remembered by the tribunal, and gives the tribunal the chance to assess their credibility and to seek information through their own questions. In short, cross-examination gives a platform to an opposing witness.11

A. Cross-examination of fact witnesses


In relation to fact witnesses, cross-examination presents “an opportunity to undermine the credibility of an adverse witness and facilitates the alteration of the tribunal’s perception of the opponent’s evidence”.12


However, one of the difficulties is that for the duration of cross-examination, counsel must deal with a witness whose reaction to cross-examination cannot necessarily be anticipated.


When preparing cross-examination, it is fundamental that counsel ask him/herself whether it is necessary to cross-examine a specific witness, what would realistically be obtained from a witness and whether it will help the client's case. Accordingly, there is usually no point cross-examining a factual witness just for the sake of it.13

B. Cross-examination of expert witnesses


In comparison with factual witnesses, the cross-examination of expert witnesses demands a more complete knowledge of the case, painstaking preparation and a trained questioning technique.


Expert evidence may cover a wide variety of topics, “such as defects in the design of software, delay in the construction of infrastructure projects, the chemical composition of pharmaceuticals, the valuation of expropriated investments and questions of law. To conduct an effective cross-examination, it is necessary to become immersed in the relevant subject matter in a focused and practical way, usually by working closely with your client and own expert witness”.

III. Comparison between IBA and Prague Rules on cross-examination


Article 5 of the Prague Rules states that an arbitral tribunal has the power to decide which witness is to be called for examination, and it may decide not to call the witness for examination if it considers the testimony to be unnecessary, or if the witness statement has already been submitted. Thus, Article 5 also does not provide for an unconditional approach in favour of cross-examination. On the contrary, Article 4 of the IBA Rules on the Taking of Evidence requires the fact witness to appear for testimony at the evidence hearing. If the witness has no valid reason for absence the witness statement of such a witness shall be the disregard.14

IV. Practical suggestions


In certain jurisdictions there are strict rules to be followed when conducting examination of a witness. These include, among others, the obligation of not using leading questions during the direct examination of a witness, the situations in which leading questions are appropriate (including on cross-examination)15 or the scope of cross-examination that should not go beyond the subject matter of a direct examination.16


In international arbitration such strict rules do not exist, but a cross-examination focusses on the content of the witness statement. Practitioners follow different approaches when conducting cross-examination but the following principles are generally used when preparing for and conducting a cross-examination:

  • Basic principle no. 1: be fully prepared.
  • Basic principle no. 2: be brief.
  • Basic principle no. 3: use only leading questions.
  • Basic principle no. 4: use only short, simple, unambiguous questions.
  • Basic principle no. 5: listen carefully to the answer.
  • Basic principle no. 6: do not ask for conclusions.
  • Basic principle no. 7: do not let the witness repeat the direct testimony.
  • Basic principle no. 8: do not let the witness explain.
  • Basic principle no. 9: exercise self-control and control the witness. Do not argue, get angry, with the witness.17
  • Basic principle no. 10: ask only a few innocuous questions to which you know the answers, or even to ask no questions at all”.18


Wellman, F., The Art of Cross-Examination, Touchstone, 1997.

Younger, I., The Ten Commandments of Cross-Examination.

Stern, H., Trying Cases to Win, Vol. III: Cross-Examination, LawbookExchange, 1993.

Kehoe, E., Cross Examination and Re-Cross in International Arbitration, in The Art of Advocacy in International Arbitration, 2nd ed., Juris Publishing, 2010.

Newman, L. and Sheppard, B., Take the Witness: Cross Examination in International Arbitration, Juris Publishing, 2010.

Hobér, K. and Sussman, H.S., Cross-Examination in International Arbitration: Nine Basic Principles, Oxford Press, 2014.

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