Final State Interaction Effects on $\gamma$ from $B \to D K$

The implications of a negligible annihilation contribution in $B \to D K$ decays are reanalyzed and are shown to lead to no new constraints on the weak phase $\gamma$ from color-allowed $B^{\pm} \to D K^{\pm}$ decays. A test of negligible annihilation is proposed in $B^+ \to D^+ K^0$ (or $B^+ \to D^+ K^{*0}$), and an application is presented in which $\gamma$ can be determined from these processes (or corresponding $B \to D K^*$ decays) supplemented with isospin-related neutral $B$ decays.