Article 8 of Law No. 12 of 1963 concerning the Rules of Procedure of the National Assembly

The committee may decide to summon the challenger, the person whose membership is challenged, or witnesses, request any papers from the Government for examination, and take whatever measures it considers conducive to establishing the truth. It may appoint from among its members one or more subcommittees to conduct investigations. Witnesses shall be summoned by a letter from the Speaker of the Council at the committee's request, by registered mail or through the special register of the Council's correspondence.