Testimonial evidence, despite some acknowledged criticalities, is still one of the main means of proof and instruments to ascertain a fact in the arbitration process. The practice of the big courts has assumed a favor towards documentary evidence, mainly for the certainty and clarity that this type of evidence has compared to the testimony. However, this is only the current attitude of the big courts, but for a large part of the history of the arbitration process, testimonial evidence has been the great protagonist mainly because the English model, and more generally the common law model, provides for testimonial evidence as suitable to ensure the most valid and useful information for the purposes of the decision of the dispute. However, before going on to analyze the differences between the two major legal systems and finally analyze the solution of the arbitration practice, it is appropriate to define and frame the testimony as a means of evidence. A witness is a person who has direct or indirect knowledge about the facts relevant to the case. Interrogation has the primary function of providing relevant information, allowing a description of the facts, and making the judge instantly aware of the words, feelings, and arguments of the witness. Closely related to the content of the testimony is the credibility of the subject called to testify. In this type of evidence, the human component is the main part and therefore it is necessary to analyze well the credibility of the subject, to give the right weight and evaluation to the arguments. It often happens that in the same testimony or on several occasions, the witness shows limits to his knowledge, says inconsistencies, or omits to say things, thus greatly reducing his credibility before the judge.
In common law systems, where witness evidence is the protagonist, several interrogation techniques and methods have been developed over the years which can bring an advantage to the lawyers who use them. In fact, in these proceedings, the interrogation of the witness, in addition to the informative function, allows the lawyer to show off all his rhetorical skills by highlighting or presenting under a different light some facts of the case and also allowing to expose the case again, not directly as it happens in written pleadings, but indirectly through a third person. In these systems the interrogation becomes a real procedural phase of considerable importance as pointed out by some commentators: “Cross-examinations are not conducted in isolation. They are part of the total trial plan…. The purposes of cross are to preserve and build upon your case theory or demolish the other side’s, and in this way to persuade the tribunal.”
Also, for this reason, lawyers at common law always prefer to use the technique of cross-examination so that they always have the active power to manage the course of the trial. In contrast, in civil law systems, as with other forms of evidence, the active power remains with the judge. The lawyers can formulate specific questions, by subdividing them into single chapters, and then the judge, if he admits them, will formulate them to the witness. Therefore, only the judge, can ask a witness question and only when he deems it necessary, he can ask for further clarifications. Obviously in civil law systems, due to the rigidity of the discipline, the rhetorical function is completely lacking, and the testimony becomes an aid to the other evidence brought.
In matters of testimony, the practice of the great arbitration tribunals leaves full freedom to the parties to question their own witnesses and the witnesses of the opposite party, conforming to the common law system. This freedom of choice to directly interrogate witnesses is confirmed in sec. 4 of the Iba rules, which regulates the role and modalities of the testimony, also providing the witness Statement, i.e. a declaration made and signed by the witness where, in addition to the generalities and the content of the statements, he/she declares that the statements made are true. This possibility of questioning the witness by the lawyers is also regulated, as regards its modalities, in sec. 8 of the same Iba rules of 2020 “Evidentiary Hearing” in which the modalities by which the questioning of the witness are carried out are stated, reiterating also the powers of the court and the parties. 
Written witness statements have now become an established practice for the courts, partly because they allow the questioning to be confined to certain topics, saving money and time. The written statement is always followed by the questioning of the party who made it, again there will be cross examination of the subject. If the witness who made and signed the statement does not show up, then the written statement will be unusable and the testimony will be inadmissible, unless there is a justified reason for absence or there is an agreement between the parties to that effect, but the scope and weight of the statement will be reduced. This practice is also well demonstrated by the guidelines of soft law such as sec. 4 of the Iba rules, sec. 8.5 of the same Iba rules  and the ICC Commission’s report on Time and Cost Control in Arbitration (“2012 ICC Time and Costs Report”).
The weight of the statement and then of the following testimony are decided and evaluated by the arbitrator according to the same yardstick and the same principle of free belief. As already mentioned, the human component in this means of evidence is essential and therefore it is also essential for the arbitrator to evaluate it. That is why in a testimony the behavior and status of the person questioned assume a greater weight, and it is essential to investigate whether there is any relationship between the parties and the witness so as to judge the objectivity of the latter.
Normally, the examination of witnesses takes place at a hearing that is reserved for the collection of this type of evidence, so that the lawyers can prepare the line of questioning during the interrogation in advance. The hearing, precisely because of the type of evidence, is generally in presence, to allow the referee to know and directly see the attitude and behavior of the witness. Recently, due to the Covid-19 pandemic and the development of so-called cyber-tribunals, in-person hearings have been transformed into virtual hearings with the help of technology. Confirming the need and the trend to use virtual tools to put the parties of the arbitration process in touch, there are new rules provided by the ICC  and the 2020 Iba rules  as well as other permanent arbitral institutions such as the LCIA and the Italian CAM. The difficulty of these new modalities of the witnesses examinations are more than anything else in the authentication of the identity of the subject who is interrogated and in the evaluation of the arbitrators who do not have a personal view of the subject during the interrogation. Obviously, the opening to these tools brings a revolution of the entire vision that until now was head of the witnesses interrogation, certainly leaving room for a revision of the discipline and a change in the modus operandi of arbitrators and lawyers. The use of these tools, however, also has several positive elements for the parties, mainly it allows to drastically reduce the costs and timing of the process, avoiding travel and delays due to the obligation to be present in court.
As for the possibility of hearing testimony from persons interested in the case, this is generally recognized in international arbitrations and indeed often used. Although in many national legal systems it is prohibited to admit the testimony of persons who have an interest in the case, there are no rules in arbitration, as it was well pointed out in the Dillon case: “Unimpeached testimony of a person who may be the best informed person regarding transactions and occurrences under consideration cannot properly be disregarded because such a person is interested in a case. No principle of domestic or international law would sanction such an arbitrary disregard of evidence.” Obviously the weight of the testimony will be evaluated in preference to the interest of the subject, and it will be necessary to evaluate the genuineness of the testimony and the objectivity of the reasons. Normally this type of witnesses is heard only to corroborate or give greater plausibility to evidence already presented and not as the only informative tool.
Cross-examination is a technique of interrogation of Anglo-Saxon derivation that over the years has become the cultural and legal heritage of all countries of common law also influencing the other legal traditions of civil law and even in international arbitrations the witness is questioned by using this interrogation technique. Cross-examination is based on three different phases, one fixed and the other two only possible. The first is the direct examination of the witness by the requesting lawyer, the second phase is cross-examination by the opposing party (in this case the opposing lawyer may decide that he or she does not want to cross-examine the witness), and the last phase is reexamination where the requesting lawyer re-interrogates the witness. Each of these examinations has its own specific task and function, although, as some authors well point out, the true purpose of all the three witness examinations is: “to let you argue your case during the testimony of the other side’s witnesses. Every witness they put on the stand is another opportunity to give part of your summation right in the middle of their case”. However, if one wants to find a specific function to these phases, the direct examination of the witness has the main purpose of providing the requested information and of presenting the case again before the arbitrator. In this case the object of the questions generally concerns the relevant facts of the case. In contrast, cross-examination does not have the sole purpose of providing information, but rather has the function of discrediting and destroying the statements made during direct examination. In this case, during the cross-examination, the lawyer will have the task of diminishing the weight and value of the testimonial evidence as much as possible, trying to damage and diminish the credibility, knowledge, and authenticity of the testimony and, when possible, trying to prove facts favorable to his own reasons. The function of the re-examination is to give a “correction” after what has emerged from the cross-examination of the opposing party. Unless new elements have emerged, the purpose is no longer purely informative, but its aim is to restore the credibility and value of the evidence.
As mentioned above, cross-examination has become a fundamental tool for all common law traditions and has been defined by John Henry Wigmore as follows: “Cross-examination is the greatest legal engine ever invented for the discovery of truth.” The Anglo-American doctrine is full of these phrases and quotations, so full of emphasis and so theatrical, precisely because of the role that this technique has played and how it has become rooted in the legal culture of these countries, becoming the pivot for judicial decisions.
Cross-examination is not to be considered only as a tool to seek information from a witness, but, on the contrary, many authors have pointed out how this interrogation technique often leads, more than to find the truth, to understand when a testimony or evidence collected is not very credible or even false, as it is also stated in the case Mechanical and General Inventions Co. v. Austin in which: “Cross-examination is a powerful and valuable weapon for the purpose of testing the veracity of a witness and the accuracy and completeness of his story” and again in the case United States v. Salerno : “Even if one does not completely agree with Wigmore’s assertion that cross-examination is ‘beyond any doubt the greatest legal engine ever invented for the discovery of truth’, one must admit that in the Anglo-American legal system cross-examination is the principal means of undermining the credibility of a witness whose testimony is false or inaccurate”
Precisely because of the role of this technique, the complex way of using it and the unpredictability that the human component of the witness may have, cross-examination, to be used correctly and in a functional way for one’s own reasons, must be studied in detail and rules must be followed in order not to fall into error. Obviously, universities in common law countries study all the various techniques to learn how to master it and how to use rhetoric as a weapon for an expert lawyer. There is not, of course, a unique and univocal way to use this method of questioning, and the ability of a good lawyer lies precisely in knowing how to adapt to the concrete case, immersing himself/herself in the moment and understanding the subject to which the questions are addressed. It is not surprising, therefore, that in practice, every single hearing creates its own social microcosm, witnesses interact with lawyers and arbitrators in a unique and always different way generating, even unconsciously, evaluations, opinions, sympathies, and hostilities that can be used to persuade the arbitrator of their reasons. 
The questions asked can vary and can be leading questions, where the lawyer “guides” the witness almost by putting words in his/her mouth, or closed questions, where the witness is forced to answer only yes and no, or open questions, where the witness is given carte blanche to argue as he sees fit. Each type of question corresponds to an objective and a type of person in front of the witness, for example, when the witness is a technical expert, asking a closed question when you are not sure of the answer can be very counterproductive. Moreover, even not asking questions can often be a winning move, also because you must always remember that the referee considers every behavior in order to convince himself/herself of the truth. All this is overcome, at least partially, in international arbitrations, because of the witness statement, which we have already spoken about, that allows to know the statements of the witnesses because they have already been written.
Even for lawyers specializing in arbitration litigation, the so-called ten commandments of Professor Irving Younger stand out among the many rules to conduct a good cross-examination. He formulates ten simple rules to be respected if you want to use this tool well. They are:
- Be Brief
Be brief, short and succinct. Why? Reason 1: chances are you are screwing up. The shorter the time spent, the less you will screw up. Reason 2: A simple cross that restates the important part of the story in your terms is more easily absorbed and understood by the jury. You should never try to make more than 3 points on cross-examination. Two points are better than three and one point is better than two.
- Use Plain Words
The jury can understand short questions and plain words. Drop the 50 dollar word in favor of the 2 dollar word. “Drive you car” instead of “operate your vehicle.”
- Use Only Leading Questions
The law forbids questions on direct examination that suggest the answer. The lawyer is not competent to testify. On cross-examination the law permits questions that suggest the answer and allows the attorney to put his words in the witnesses’ mouth. Cross-examination, therefore, specifically permits you to take control of the witness, take him where you want to go, and tell your important point to the jury through the witness. Not asking controlled leading questions leaves too much wiggle room. What happened next? I would like to clear up a couple of points you made on direct? These questions are the antithesis of an effective cross-examination. Any questions which permit the witness to restate, explain or clarify the direct examination is a mistake. You should put the witness on autopilot so that all of the answers are series of yes, yes, yes.
- Be Prepared
Never ask a question that you do not know the answer to. Cross is not a fishing expedition in which you uncover new facts or new surprises at the trial.
Listen to the answer. For some, cross-examination of an important witness causes stage fright; it confuses the mind and panic sets in. You have a hard time just getting the first question out, and you’re generally thinking about the next question and not listening to the answer.
- Do Not Quarrel
Do not quarrel with the witness on cross-examination. When the answer to your question is absurd, false, irrational contradictory or the like; Stop, sit down. Resist the temptation to respond with “how can you say that, or how dare you make such an outrageous claim?” The answer to the question often elicits a response, which explains away the absurdity and rehabilitates the witness.
- Avoid Repetition
Never allow a witness to repeat on cross-examination what he said on direct examination. Why? The more times it is repeated, the more likely the jury is to believe it. Cross-examination should involve questions that have nothing to do with the direct examination. The examination should not follow the script of the direct examination.
- Disallow Witness Explanation
Never permit the witness to explain anything on cross-examination. That is for your adversary to do.
- Limit Questioning
Don’t ask the one question too many. Stop when you have made your point. Leave the argument for the jury.
- Save for Summation
Save the ultimate point for summation. A prepared, clear and simple leading cross-examination that does not argue the case can best be brought together in final summation.”
These rules are the basis to conduct an interrogation. Knowing, studying, and being accustomed to handling cross-examination is essential in international arbitrations with parties from very different systems, because it provides an advantage over the civil law lawyer that is often difficult to overcome. Conversely, when both parties are not accustomed to this type of witness examination, they are unlikely to advocate questioning witnesses personally, preferring to put the questions in writing and have the arbitrators conduct the questioning.
See A. C. Sinclair, Differences in the Approach to Witness Evidence between the Civil and Common Law Traditions, in D. Bishop, E. G. Kehoe (eds) The Art of Advocacy in International Arbitration, JurisNet LLC, 2010 2nd ed, p. 41.
 R. H. Clark, G. R. Dekle, W. S. Bailey, Cross-Examination Handbook: Persuasion, Strategies, and Techniques, Wolters Kluwer; 2015 2nd ed., p. 6.
 See sec. 4.5 of 2020 Iba rules: “Each Witness Statement shall contain: (a) the full name and address of the witness, a statement regarding his or her present and past relationship (if any) with any of the Parties, and a description of his or her background, qualifications, training and experience, if such a description may be relevant to the dispute or to the contents of the statement; (b) a full and detailed description of the facts, and the source of the witness’s information as to those facts, sufficient to serve as that witness’s evidence in the matter in dispute. Documents on which the witness relies that have not already been submitted shall be provided; (c) a statement as to the language in which the Witness Statement was originally prepared and the language in which the witness anticipates giving testimony at the Evidentiary Hearing; (d) an affirmation of the truth of the Witness Statement; and (e) the signature of the witness and its date and place.”
 See sec. 8.3 and 8.4 of 2020 Iba rules: “The Arbitral Tribunal shall at all times have complete control over the Evidentiary Hearing. The Arbitral Tribunal may limit or exclude any question to, answer by or appearance of a witness, if it considers such question, answer or appearance to be irrelevant, immaterial, unreasonably burdensome, duplicative or otherwise covered by a reason for objection set forth in Articles 9.2 or 9.3. Questions to a witness during direct and re-direct testimony may not be unreasonably leading. 4. With respect to oral testimony at an Evidentiary Hearing: (a) the Claimant shall ordinarily first present the testimony of its witnesses, followed by the Respondent presenting the testimony of its witnesses; (b) following direct testimony, any other Party may question such witness, in an order to be determined by the Arbitral Tribunal. The Party who initially presented the witness shall subsequently have the opportunity to ask additional questions on the matters raised in the other Parties’ questioning; (c) thereafter, the Claimant shall ordinarily first present the testimony of its Party-Appointed Experts, followed by the Respondent presenting the testimony of its Party-Appointed Experts. The Party who initially presented the PartyAppointed Expert shall subsequently have the opportunity to ask additional questions on the matters raised in the other Parties’ questioning; (d) the Arbitral Tribunal may question a TribunalAppointed Expert, and he or she may be questioned by the Parties or by any PartyAppointed Expert, on issues raised in the 22 Tribunal-Appointed Expert Report, in the Parties’ submissions or in the Expert Reports made by the Party-Appointed Experts; (e) if the arbitration is organised into separate issues or phases (such as jurisdiction, preliminary determinations, liability and damages), the Parties may agree or the Arbitral Tribunal may order the scheduling of testimony separately for each issue or phase; (f) the Arbitral Tribunal, upon request of a Party or on its own motion, may vary this order of proceeding, including the arrangement of testimony by particular issues or in such a manner that witnesses be questioned at the same time and in confrontation with each other (witness conferencing); (g) the Arbitral Tribunal may ask questions to a witness at any time.”
 See sec. 8.5 of 2020 Iba rules: “A witness of fact providing testimony shall first affirm, in a manner determined appropriate by the Arbitral Tribunal, that he or she commits to tell the truth or, in the case of an expert witness, his or her genuine belief in the opinions to be expressed at the Evidentiary Hearing. If the witness has submitted a Witness Statement or an Expert Report, the witness shall confirm it. The Parties may agree or the Arbitral Tribunal may order that the Witness Statement or Expert Report shall serve as that witness’s direct testimony, in which event the Arbitral Tribunal may nevertheless permit further oral direct testimony.”
 See par. 78 of 2012 ICC time and Costs Report: “Cost and time can be saved by limiting or avoiding direct examination of witnesses. When appropriate, witness statements can substitute for direct examination at a hearing”
 See ICC’s “Rule 2021” on https://iccwbo.org/dispute-resolution-services/arbitration/rules-of-arbitration/#:~:text=The%20below%20ICC%20Rules%20of,the%20world%20to%20resolve%20disputes, the provision of article 26 which “opens up” the possibility of conducting virtual hearings “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. When a hearing is to be held, the arbitral tribunal, giving reasonable notice, shall summon the parties to appear before it on the day and at the place fixed by it. The arbitral tribunal may decide, after consulting the parties, and on the basis of the relevant facts and circumstances of the case, that any hearing will be conducted by physical attendance or remotely by videoconference, telephone or other appropriate means of communication”
 See art. 8.2 of 2020 Iba rules: “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. The protocol may address: (a) the technology to be used; 21 (b) advance testing of the technology or training in use of the technology; (c) the starting and ending times considering, in particular, the time zones in which participants will be located; (d) how Documents may be placed before a witness or the Arbitral Tribunal; and (e) measures to ensure that witnesses giving oral testimony are not improperly influenced or distracted.”
 See case Montijo v. Guatemala, in, J.B Moore, International Arbitrations, 1898, vol. 2, pp. 143
 Dillon v. Mexico, United States and Mexico General Claims Commission, Opinions of Commissioners, 1929, p.6
 J. W. Mcelhaney, The Real Purpose of Cross-Examination, 22 Litigation n.3, p. 53
 D. J. A. Cairns, The premises of witness questioning in international arbitration on https://www.cremades.com/
 J. H. Wigmore, Evidence in Trials at Common Law vol. V, 1974, p. 1367
 See Mechanical etc. Co. Ltd. v Austin  AC. 346 at p. 359
 See United States v. Salerno 505 U.S. 317, 1992, p. 328
 S. Jagusch, Cross-Examination of Fact Witnesses: The Common Law Perspective, Quinn Emanuel Urquhart & Sullivan LLP, 2019, on https://globalarbitrationreview.com/
 Summarized from Irving Younger,The Art of Cross-Examination. The Section of Litigation Monograph Series, No. 1, published by the American Bar Association Section on Litigation, from a speech given by Irving Younger at the ABA Annual Meeting in Montreal Canada in August of 1975. On https://www.nebarfnd.org/sites/default/files/2019-04/10commandments.pdf