  The quantity P_{mu}^{pi}xi, where xi is one of the muon decay parameters and
$P_{\mu}^{\pi}$ is the degree of muon polarization in pion decay, has been
measured. The value P_{mu}^{pi}xi = 1.0003 +- 0.0006 stat. +- 0.0038 syst. was
obtained. This result agrees with previous measurements but is over a factor of
two more precise. It also agrees with the Standard Model prediction for
P_{mu}^{pi}xi and thus leads to restrictions on left-right symmetric models.
