Method of constraining the {ital CP}-violating phase {gamma} from charged {ital B} meson decays

Gronau, Rosner, and London have presented a method of determining the {ital CP}-violating phase {gamma} of the CKM matrix from the decays {ital B}{sup +}{r_arrow}{pi}{sup +}{ital K}{sup 0} and {ital B}{sup {plus_minus}}{r_arrow}{ital K}{sup {plus_minus}}{pi}{sup 0}. We show that this method could provide a powerful constraint on {gamma} even if only a weak upper limit on the {ital CP} violation is obtained. We also point out a consequence of the assumptions they make.