  We discuss recent work which identifies a potential flaw in standard
treatments of weak decay amplitudes, including that of epsilon'/epsilon. The
point is that (contrary to conventional wisdom) dimension-eight operators
contribute to weak amplitudes at order G_F alpha_s and without 1/M_W^2
suppression. The effect of dimension-eight operators is estimated to be at the
100% level in a sum rule determination of the operator Q_7^(6) at mu = 1.5 GeV,
suggesting that presently available values of mu are too low to justify the
neglect of these effects.
