The current judiciary of Niger was established with the creation of the Fourth Republic in 1999. The constitution of December 1992 was revised by national referendum on 12 May 1996 and, again, by referendum, revised to the current version on 18 July 1999. It is an inquisitorial system based on the Napoleonic Code, established in Niger during French colonial rule and the 1960 constitution of Niger. The Court of Appeals reviews questions of fact and law, while the Supreme Court reviews application of the law and constitutional questions. The High Court of Justice (HCJ) deals with cases involving senior government officials. The justice system also includes civil criminal courts, customary courts, traditional mediation, and a military court. The military court provides the same rights as civil criminal courts; however, customary courts do not. The military court cannot try civilians.
Niger's independent judicial system is composed of four higher courts — the Court of Appeals, the Supreme Court, the High Court of Justice and the Court of State Security — as well as lower criminal, civil and appeals courts.
Nigeren law is based on the French legal system, in which investigative judges develop and bring to trial criminal cases which they judge. Criminal courts are based on this "investigating magistrate" system. Appeals courts – up to and including the Supreme Court of Niger – are panels of professional judges who hear criminal appeals.
The 1999 constitution and Nigerien law require a warrant for an arrest, and this generally is observed in practice, outside areas under special states of emergency, such as the entire Agadez Region between 2007 and 2009. Judges and prosecutors weigh evidence and issue warrants accordingly. Persons are brought before an independent judiciary.
Those arrested must be notified of their right to a lawyer within 24 hours of detention. Nigerien law allows individuals to be detained initially for up to 48 hours without charge, and allows an additional 48-hour detention period if police need more time to gather evidence. Detainees have a right to prompt judicial determination. Security forces must inform detainees of the charges against them promptly. Law provides for a maximum pretrial confinement of 30 months for serious crimes and 12 months for minor offenses, with special extensions in certain sensitive cases.