NARTEY-TOKOLI AND OTHERS v. VOLTA ALUMINIUM CO. LTD. Labour—Collective agreement—Capacity to negotiate—Alternative to Collective agreement—ICU and Valco only parties to collective agreement (exhibit A) for employees of Valco—Valco subsequently negotiating "leave of absence without pay/recall programme (L.O.A.) with local union and WDC-ICU's power to negotiate not delegated to local union—No authority from I.C.U. to local union to negotiate L.O.A.—L.O.A. meant as alternative to exhibit A—Whether L.O.A. enforceable against employees of Valco.