[en] The results of symmetry investigation and field theory formulation in the unified space are used to obtain the isotopic selection rules for the decays of nonstrange and strange particles. It is shown that in accounting for the intrinsic characteristics of leptons, photons and spurions, simultaneously with hadrons, the selection rules are: ΔI₃=0, ΔSsub(t)=0, (ΔB=ΔL=ΔQ=0), where I is the isotopic spin, Ssub(t) is the total strangeness (Ssub(t)=S+R, R is a new strange number). For the illustration purpose, some cases of the decays is considered