  The phases of terms of amplitude that arise from the $\pi\pi$ interaction are
obtained by using a simple realistic model of $\pi\pi$ interaction via virtual
$\rho$-meson, instead of the ChPT. It is shown that the standard ChPT approach
cannot reproduce the contribution of the $\rho$-meson to the $\pi\pi$
interaction. It is shown that the interference between the terms of amplitude
with different CP-parity appears only when the photon is polarized (linearly or
circularly). Instead of measuring the linear polarization, the angular
correlation between the $\pi^{+}\pi^{-}$ and $e^{+}e^{-}$ planes in
$K_{S,L}\to\pi^{+}\pi^{-}e^{+}e^{-}$ decay can be studied.
