Jurisdiction is a threshold matter. Once raised all proceedings abate until it is resolved. Proceedings conducted without jurisdiction amount to a nullity. There is nothing as useless as conducting a trial flawlessly only to find out that the court had no jurisdiction to hear the matter. That explains why the issue of jurisdiction can be taken at any stage of the proceedings, at trial, on appeal and even in the Supreme Court for the first time.
– Rhodes-Vivour, JSC. Olabomi v. Oyewinle (2013) – SC.345/2012