We demonstrate how the transverse \tau ⁺\tau ^- spin correlations can be used to determine whether a decaying Higgs boson is a mixed  CP eigenstate, thereby directly probe the presence of  CP violation in the neutral Higgs boson sector. We investigate the subsequent decay chain H \to \tau ⁺\tau ^- \to \rho ⁺\bar {\nu }_\tau \rho ^-\nu _\tau \to \pi ⁺\pi ⁰\bar {\nu }_\tau \pi ^-\pi ⁰\nu _\tau . The prospects for the measurement of the pseudoscalar admixture in the H\tau ⁺\tau ^- coupling to a Standard Model Higgs boson with a mass of 120 GeV are quantified for the case of e⁺e^- collisions at 350 GeV center-of-mass energy and 1 {ab}^-1 integrated luminosity. The Standard Model Higgsstrahlung production process is used as an example.

PACS numbers: 14.60.Fg, 14.80.Bn, 14.80.Cp