By virtue of section 233 of the 1999 Constitution of Nigeria and section 22 of the Supreme Court Act Cap 15 Laws of Nigeria 2004, the word leave means permission. Therefore an appellant is bound, where necessary to seek the formal permission of the court below before setting an appeal in process. Leave of court where it is required is a condition precedent to the exercise of the right to appeal. This failure to obtain leave where it is required will render any appeal filed incompetent as no jurisdiction can be conferred on the appellate court. Hence an appeal from the Court of Appeal to the Supreme Court on grounds other than of law alone is incompetent and invalid unless leave of either the Court of Appeal or the Supreme Court is first sought and obtained.
– Adekeye JSC. Nwaolisah v. Nwabufoh (2011)