The helical nanowires of a chiral sculptured thin film (CSTF) were taken to be made from a weakly dissipative material while the void regions between nanowires were filled with an active material, and the planewave reflection/transmission characteristics were investigated numerically. The CSTF was found to simultaneously amplify left-circularly polarized incident light and attenuate right-circularly polarized incident light, or vice versa, depending upon its structural handedness. This polarization-state-dependent attenuation and amplification phenomenon is sensitive to the direction of incidence and the thickness of the CSTF. Furthermore, the presence of both dissipative and active materials allows the high reflectance to exceed unity across a substantial proportion of the circular Bragg spectral regime for incident light of one circular polarization state but not of the other circular polarization states. That is, the CSTF functions as a circular Bragg supermirror for one, and only one, circular polarization state.