  We show from general principles that there must be a center of mass energy,
$\sqrt s_0$, where the polarization asymmetry $A=\Delta \sigma({\gamma e \to W
\nu })/ \sigma({\gamma e \to W \nu })$ for circularly-polarized photon and
electron beams vanishes. In the case of the Standard Model, the crossing point
where the asymmetry changes sign occurs in Born approximation at $\sqrt
s_{\gamma e} = 3.1583\ldots M_W \simeq 254$ GeV. We demonstrate the sensitivity
of the position of the polarization asymmetry zero to modifications of the SM
trilinear $\gamma W W$ coupling. Given reasonable assumptions for the
luminosity and energy range for the Next Linear Collider(NLC) with a
backscattered laser beam, we show that the zero point, $\sqrt s_0$, of the
polarization asymmetry may be determined with sufficient precision to constrain
the anomalous couplings of the $W$ to better than the 1\% level at $95\%$ CL.
In addition to the fact that only a limited range of energy is required, the
polarization asymmetry measurements have the important advantage that many of
the systematic errors cancel in taking cross section ratios. The position of
the zero thus provides an additional weapon in the arsenal used to probe
anomalous trilinear gauge couplings.
