  We show that, under reasonable hypotheses, it is possible to study two-body
non-leptonic weak decays in numerical simulations of lattice QCD. By assuming
that final-state interactions are dominated by the nearby resonances and that
the couplings of the resonances to the final particles are smooth functions of
the external momenta, it is possible indeed to overcome the difficulties
imposed by the Maiani-Testa no-go theorem and to extract the weak decay
amplitudes, including their phases. Under the same assumptions, results can be
obtained also for time-like form factors and quasi-elastic processes.
