2. The requesting State shall undertake to provide the necessary protection for the security of witnesses and experts and of members of their families that is required by their situation, the circumstances of the case in connection with which they are sought and the types of risks that can be anticipated. Article 38 1. Where a witness or expert whose appearance, is sought by a requesting State is in custody in the requested State, he may be temporarily transferred to the location of the hearing where he is requested to provide his testimony under conditions and at times to be determined by the requested State. Such transfer may be refused if: a. The witness or expert in custody objects; b. His presence is required for criminal proceedings in the territory of the requested State; c. His transfer would prolong the term of his detention; d. There are considerations militating against his transfer. 2. The witness or expert thus transferred shall continue to be held in custody in the territory of the requesting State until such time as he is returned to the requested State unless the latter State requests that he be released. Part Four Final Provisions Article 39 This Convention is subject to ratification, acceptance or approval by the signatory States, and instruments of ratification, acceptance or approval shall be deposited with the General Secretariat of the League of Arab States within 30 days of the date of such ratification, acceptance or approval. The General Secretariat shall notify member States of the deposit of each such instrument and of its date. Article 40 1. This convention shall enter into force on the thirtieth day after the date as of which instruments of ratification, acceptance or approval have been deposited by seven Arab States. 2. This Convention shall enter into force for any other Arab State only after the instrument of ratification, acceptance or approval has been deposited and 30 days have elapsed from the date of that deposit. Article 41 No Contracting State may make any reservation that explicitly or implicitly violates the provisions of this Convention or is incompatible with its objectives.