decision shall be subject to appeal. ART 174: The experts shall, if necessary, present to the public the results of the technical operations they have carried out, after being sworn in to report on their investigations and findings upon their honour and conscience. During their hearing, they may consult their report and related documents. The President may, either of his/her own motion or at the request of the Public Prosecutor or the parties or their counsels, ask the experts any question within the framework of the task entrusted to them. After their presentation, the experts shall attend the proceedings, unless the President allows them to withdraw. ART 175: If, at the hearing of a trial court, a person heard as a witness or for information purposes contradicts the conclusions of an expert or brings up new technical information, the President shall ask the experts, the Public Prosecution and, where appropriate, the party claiming damages to submit their observations. That court, through a reasoned decision, shall either declare that it shall dispense with the hearing, or that the case shall be adjourned to a later date. In the latter case, the court may prescribe, with regard to the expert opinion, any measure it deems appropriate. Section VIII - Instances of Nullity of the Criminal Investigation ART 176: The provisions of Articles 103, 107, 1 08 ~ 110, 1 12. 128, 135 and 136 must be observed on pain of nullity both of the act itself and of the subsequent proceedings. Any questioning of a person charged carried out in violation of the provisions of Article 107 Paragraph 2 shall be null and void. The party in respect of whom an essential formality has been breached may waive the breach and thus regularise the proceedings. Such a waiver must be expressly stated. It shall only be made in the presence of his/her counsel, or where the latter has been duly summoned. If the investigating judge believes that an investigation act is null and void, he/she shall refer it to the Indictment Chamber for annulment, after consulting the Public Prosecutor and informing the person charged as well as the party claiming damages of this fact. If the Public Prosecutor considers a null and void act has been committed, he/she shall order the investigating judge to send him/her the case file for onward transmission to the Indictment Chamber, and shall file a motion for annulment by this Chamber. The parties and their counsel may directly seize the Indictment Chamber about any instance of nullity of proceedings which the investigating judge has not automatically taken note of. They shall inform the Public Prosecutor who shall proceed as provided in the preceding paragraph. The Indictment Chamber shall proceed as stated in Article 206. ART 177- There shall also be nullity in the event of a breach of the substantive provisions of this Part other than those referred to in Article 176, and in particular in the case of violati on of the rights of the defence. The Indictment Chamber shall decide whether the annulment must be limited to the defective act, or extend to all or part of the subsequent proceedings. ART 178: The annulled acts shall be removed from the investigation file and filed at the registry of the Court of Appeal. It shall be forbidden to collect any information from these annulled acts for use against the parties, under pain of forfeiture for the magistrates and of disciplinary prosecution for counsel. 34