A single hierarchy, several parallel tracks
Chapter VII of the 1999 Constitution — discussed for its place in the wider document in nigerian constitution — sets out Nigeria's judicature in one continuous hierarchy that nonetheless carries several parallel appellate tracks side by side: an ordinary track running through the High Courts and the Federal High Court, a labour-specific track through the National Industrial Court, and two subject-specific tracks, Sharia and customary, that exist only where the Constitution or a state chooses to establish them S1. Every track converges at the same two apex institutions, the Court of Appeal and the Supreme Court of Nigeria, which is why the system is properly described as one hierarchy rather than three separate ones S1S2S4
The Supreme Court of Nigeria
Section 230 of the Constitution establishes the Supreme Court as consisting of the Chief Justice of Nigeria and "such number of Justices of the Supreme Court, not exceeding twenty-one, as may be prescribed by an Act of the National Assembly" S1. Its original jurisdiction is narrow and exclusive — disputes between the Federation and a state, or between states, on questions of legal right — and Section 232 expressly bars the Court from being given original jurisdiction over any criminal matter S1. Its appellate jurisdiction, by contrast, is exclusive and final: Section 233 gives it sole authority to hear appeals from the Court of Appeal, and Section 235 states plainly that no appeal lies from the Supreme Court to any other body S1. A panel must have at least five Justices to sit, rising to seven for constitutional questions or for cases within the Court's original jurisdiction S1
The Court of Appeal
The Court of Appeal sits immediately below the Supreme Court and is established under Section 237 as a President of the Court plus "such number of Justices of the Court of Appeal, not less than forty-nine, of which not less than three shall be learned in Islamic personal law, and not less than three shall be learned in Customary law" S1. That built-in requirement is a direct structural consequence of the court's appellate reach: Section 240 gives it exclusive jurisdiction to hear appeals from the Federal High Court, the National Industrial Court, the High Court of the Federal Capital Territory, every state High Court, the Sharia Courts of Appeal of the FCT and of the states, the Customary Courts of Appeal of the FCT and of the states, and courts-martial and tribunals — meaning its bench must be able to review Islamic-law and customary-law appeals as competently as ordinary civil and criminal ones S1. The Court also holds original jurisdiction over petitions on whether a person was validly elected President or Vice-President S1
The federal trial-level courts
Below the Court of Appeal, several federal courts of first instance handle different subject matter across the whole federation. The Federal High Court, established under Section 249, is duly constituted with as few as one judge and hears federal-law civil and criminal matters that Section 251 assigns to it, such as revenue, banking, and companies S1. The National Industrial Court, added to the Constitution as Sections 254A–254F by the Third Alteration Act of 2010, has exclusive civil jurisdiction over labour, employment, and trade-union disputes and can sit with as few as one judge, though its criminal decisions carry a right of appeal to the Court of Appeal S1. The High Court of the Federal Capital Territory, Abuja, mirrors a state High Court but for the FCT specifically S1
State High Courts, and where Sharia and customary appeals fit
Section 270 requires a High Court for every state of the federation, each headed by a Chief Judge and constituted validly with a single judge, and each holding general civil and criminal jurisdiction within the state S1. Two further appellate courts exist alongside the state High Court wherever a state chooses to create them: a Sharia Court of Appeal, whose jurisdiction under Sections 275–279 (and the equivalent Sections 260–264 at FCT level) is confined by the Constitution's own text to "civil proceedings involving questions of Islamic personal law" such as marriage, guardianship, and inheritance among Muslims; and a Customary Court of Appeal, whose jurisdiction under Sections 280–284 (Sections 265–269 for the FCT) covers appeals on "questions of customary law" S1. Both require a minimum of three judges to sit S1. It is this narrow constitutional wording — appellate jurisdiction limited to personal and customary civil questions — that anchors the long-running debate, covered in sharia in northern nigeria, over what legal basis the twelve northern states relied on when they extended Sharia into criminal law from 2000 onward S1S3
The trial courts beneath the constitutional structure
Beneath the courts the Constitution names directly sit Magistrate Courts, Area Courts, first-instance Sharia courts, and Customary Courts, which handle the overwhelming majority of cases Nigerians actually bring but which the Constitution leaves to state law to create and structure rather than naming individually S1S3. In the twelve states that operate Sharia criminal law, these lower and upper Sharia courts — renamed from what were formerly Native and Area Courts — hear criminal cases at first instance, with appeals running up to the state Sharia Court of Appeal and, from there, into the same Court of Appeal and Supreme Court that sit over every other track in the hierarchy S3. A convicted person has a thirty-day window to appeal, and no death sentence or amputation may be carried out until a state governor personally authorizes it or the sentence is confirmed on appeal S3