Related Rule
Practice Relating to Rule 100. Fair Trial Guarantees
Section E. Necessary rights and means of defence
Senegal’s Constitution (2001), as amended in 2008, states:
No one may be convicted other than by virtue of a law which entered into force before the act was committed.
However, the provisions of the preceding paragraph shall not hinder the prosecution, trial and conviction of any person for acts or omissions which, at the time when they were committed, were defined as criminal under the rules of international law concerning acts of genocide, crimes against humanity and war crimes.
The right to a defence is absolute in all states and at every stage of the proceedings. 
Senegal, Constitution, 2001, as amended in 2008, Article 9.
Senegal’s Law Authorizing Ratification of the 2012 Agreement on the Establishment of the African Extraordinary Chambers (2012) states:
Desiring to fully demonstrate the respect it has consistently shown for its international commitments since independence, Senegal has undertaken to organize the trial for crimes and serious violations of international law committed on the territory of Chad during the period 7 June 1982 to 1 December 1990.
In order to assemble the right conditions for organizing the trial, and taking into account the decision on this matter of the ECOWAS [Economic Community of West African States] Court of Justice on 18 November 2010, the Government of the Republic of Senegal and the African Union signed an Agreement in Dakar on 22 August 2012 concerning the creation of the Extraordinary African Chambers within the Senegalese court system.
This legal instrument should enable our country to tangibly honour our international commitments by facilitating the prosecution of the alleged perpetrators of the aforementioned violations, within the framework of a just and fair trial, taking duly into account the concerns of victims, with strict respect for the right of defence, in accordance with relevant international requirements.
The Government is therefore committed, within the framework of this Agreement, to adopt the necessary laws, regulations and administrative measures for the purpose of putting in place the aforementioned judicial institutions. 
Senegal, Law Authorizing Ratification of the 2012 Agreement on the Establishment of the African Extraordinary Chambers, 2012, preamble, p. 1.