Orientational order parametersP2andP4have been determined for the nematic and smectic phases of CB9 (4-nonyl-4′-cyanobiphenyl) from Raman scattering intensity measurements. The derivations ofP2andP4from Raman intensities have been made using uniaxial or biaxial Raman tensor assumptions, but the orientational distribution function is well peaked at β = 0 only when a uniaxial tensor is used. The opposite choice of a biaxial Raman tensor and its. consequences are discussed. Negative values ofP4found in our study are shown not to affect seriously the orientational distribution. Furthermore, it is shown that such negative values, if not explained by microscopic theories, are allowed when a Landau-type phenomenological approach is used. Nevertheless, it is once more emphasized that local field effects should be taken into account.