Nigerian jurisprudence generally allows the joinder of a person as co-plaintiff or co-defendant to a suit pending before a court of first instance. Thus, under most of the rules of the courts of first instance, an application may be made by a party to a suit for the joinder of another person as a co-plaintiff or co-defendant or by a non-party for joinder as a co-plaintiff or co-defendant. The circumstances under which such joinder will be permitted are set out in the respective rules of court.
In appellate proceedings, the general position is that the parties to the appeal must be the same parties at the trial court. However, the Constitution of the Federal Republic of Nigeria, 1999 (“Constitution”) allows a person who was not originally a party to a suit at a court of first instance, to appeal as an interested party by obtaining the leave of the appellate court if he is affected or aggrieved or likely to be affected or aggrieved by the proceedings in court. In such instance, the interested party, when granted leave, will maintain his own separate appeal as there are no provisions for joinder as a co-appellant to an existing appeal.
The case is however slightly different for a party seeking to join an existing appeal as a co-respondent with a view to defending the judgment of the lower court. With regard to a person seeking to be joined as a co-respondent to an appeal, the Court of Appeal has generally interpreted the constitutional right of appeal by an interested person in favour of granting an application for joinder as a co-respondent using a ‘sufficient interest’ threshold.