  The polarization asymmetries of $t$, $\bar t$ quarks can be used in the
reaction $e^+e^-\to t\bar t\nu_e\bar\nu_e$ to measure the Higgs width, in the
Standard Model or in its extensions, and to search for non-standard CP
violating phases. As an application of the CPT theorem the Higgs width is
monitored through a CP-even, $T_N$-odd, polarization asymmetry, $B_y$. CP
violation manifests through interference at tree graph level with the resonant
Higgs amplitude. Consequently, the asymmetries are all quite sizable and can be
in the range of 10--50\% for a wide choice of the Higgs mass.
