  We propose a new method to extract the CP violating weak phase $\gamma$ in
the CKM paradigm of the Standard Model, using $B^- \to D^0 \pi^- \to f \pi^-$
and $B^- \to \bar D^0 \pi^- \to f \pi^-$ decays, where $f$ are final states
such as $K^+ \pi^-$, $K^+ \rho^-$, $K \pi\pi$, {\it etc.} We also study the
experimental feasibility of our new method. With possibility of new phases in
the CKM matrix, we re-examine some of the previously proposed methods to
determine $\gamma$, and find that it would be in principle possible to identify
$\gamma$ and a new phase angle $\theta$ separately.
