The residual birefringence in quenched and injection-molded specimens of bisphenol-A polycarbonate (BAPC) homopolymer and its copolymers with substituted bisphenol-A is investigated. The chemical modifications lead to a different stress-optical behavior in the melt and glass state, which generates differences in the residual birefringence of molded specimens. In this way the origins of the residual birefringence can be interpreted in a better way. In quenched samples it is found that the level of birefringence depends on the stress-optical coefficient in the glassy state, but the unbalance of the birefringence distributions scales with the stress-optical coefficient in the melt state. This supports the idea that transient thermal stresses present during vitrification induce molecular orientation, which is responsible for the unbalance of the distributions. The residual birefringence distributions in injection-molded specimens all display a broad plateau in the core, as is usually observed in BAPC. The level of the plateau is found to scale with the stress-optical coefficient of the melt state. This is a proof for the interpretation of this plateau being induced by transient thermal stresses during vitrification and not by residual stresses. It cannot be eliminated by optimizing molding conditions but only by drastically reducing the stress-optical coefficient in the melt state.