The effects of isospin-symmetry breaking on proton emission following &bgr;-decay to the isobaric analog state are discussed in detail. Of particular importance is the mixing with a dense background of lower isospin states, whose properties are not well known. The possibility of observingT=4states in even-even,N=Znuclei, which is viable if the decay proceeds via isospin-forbidden particle emission, is also discussed. ©2000 American Institute of Physics.