  Determinations of the CKM phase $\gamma$ from weak nonleptonic $B$ decays are
affected by electroweak (EW) penguins and rescattering effects. In this talk it
is explained how the EW penguin effects can be controlled with the help of
SU(3) symmetry, by relating them to tree-level amplitudes. The impact of the
final-state interactions on the determination of $\gamma$ from $B^+\to K\pi$
decays is studied numerically, showing that they can be important. A few
alternative methods are discussed which use additional decays to eliminate
their effects.
