It is now settled firstly, that a judgment or order of a court of competent jurisdiction, remain valid and effective, unless it is set aside by an appeal court or by the lower court itself if it found that it acted without jurisdiction. See the cases of Ogueze v. Ojiako (1962),SCNLR 112; (1962) 11 All NLR 58 at 61; Williams v. Sanusi (1961) All NLR 334 at 337; Odiase v. Agbo (1972) 1 All NLR (Pt.1) 170 at 176; Melifonwu v. Egbuyi (1982) 9 SC 145; Ajao v. Alao (1986) 5 NWLR (Pt. 45) 802 at 823 and many others. Secondly, in the absence of statutory authority or except where the judgment or order is a nullity, one Judge, has no power, to set aside or vary the order of another Judge of concurrent and co-ordinate jurisdiction. See the cases of Amanabu v. Okafor (1966) 1 All NLR 205 at 207; Okorodudu v. Ejuetami (1967) NMLR 282 at 283; Akporue & Anor v. Okei (1973) 12 SC 137; Uku v. Okumagba (1974)1 All NLR (Pt. 1)475; Wimpey(Nig.)Ltd. v. Balogun (1986) 3 NWLR (Pt. 28) 324 at 331 and Orthopaedic Hospital Management Board v. B. B. Apugo & Sons Ltd. (1990) 1 NWLR (Pt.129) 652 at 657 just to mention but a few. The rationale or reason for this, is because, it is now firmly established that there is only one High Court in a State.
— I.F. Ogbuagu, JSC. Witt Ltd. v Dale Power (2007) – SC.240/2000