(_d_) A defendant shall have the right to conduct his own defense before the Tribunal or to have the assistance of Counsel. (_e_) A defendant shall have the right through himself or through his Counsel to present evidence at the Trial in support of his defense, and to cross-examine any witness called by the Prosecution. V. POWERS OF THE TRIBUNAL AND CONDUCT OF THE TRIAL =Article 17.= The Tribunal shall have the power (_a_) to summon witnesses to the Trial and to require their attendance and testimony and to put questions to them, (_b_) to interrogate any Defendant, (_c_) to require the production of documents and other evidentiary material, (_d_) to administer oaths to witnesses, (_e_) to appoint officers for the carrying out of any task designated by the Tribunal including the power to have evidence taken on commission. =Article 18.= The Tribunal shall (_a_) confine the Trial strictly to an expeditious hearing of the issues raised by the charges, (_b_) take strict measures to prevent any action which will cause unreasonable delay, and rule out irrelevant issues and statements of any kind whatsoever, (_c_) deal summarily with any contumacy, imposing appropriate punishment, including exclusion of any Defendant or his Counsel from some or all further proceedings, but without prejudice to the determination of the charges. =Article 19.= The Tribunal shall not be bound by technical rules of evidence. It shall adopt and apply to the greatest possible extent expeditious and non-technical procedure, and shall admit any evidence which it deems to have probative value. =Article 20.= The Tribunal may require to be informed of the nature of any evidence before it is offered so that it may rule upon the relevance thereof. =Article 21.= The Tribunal shall not require proof of facts of common knowledge but shall take Judicial notice thereof. It shall also take judicial notice of official governmental documents and reports of the United Nations, including the acts and documents of the committees set up in the various allied countries for the investigation of war crimes, and the records and findings of military or other Tribunals of any of the United Nations. =Article 22.= The permanent seat of the Tribunal shall be in Berlin. The first meetings of the members of the Tribunal and of the Chief Prosecutors shall be held at Berlin in a place to be designated by the Control Council for Germany. The first trial shall be held at Nuremberg, and any subsequent trials shall be held at such places as the Tribunal may decide. =Article 23.= One or more of the Chief Prosecutors may take part in the prosecution at each Trial. The function of any Chief Prosecutor may be discharged by him personally, or by any person or persons authorized by him.