[en] We have obtained α-particle angular-correlation data for the α-unbound 3^- level at E_x=9.64 MeV in ¹²C, populated in ¹²C+¹²C inelastic scattering at five energies from E_c.m.=26 to 38.0 MeV. This energy region corresponds to that where previous excitation function measurements have revealed a strong resonance in several reaction channels in the ¹²C+¹²C system. An array of four Double-Sided silicon Strip Detectors (DSSDs) was used to detect the three alpha particle from the decaying ¹²C nucleus. The angular distributions of the α particles in the ¹²C(3^-)→α +⁸Be_g.s. decay are fitted to yield the 12¹²C(3-) magnetic-substate population as a function of ¹²C scattering angle. This magnetic-substate decompostition of the inelastic scattering cross section provides information about the resonance decay l values, and the resonance spin. The data will be discussed in the context of some recent reaction-model calculation, for ¹²C+¹²C inelastic scattering