  Discovery of the CP-violation in the lepton sector is one of the challenges
of the particle physics. We search for possible principles, symmetries and
phenomenological relations that can lead to particular values of the
CP-violating Dirac phase, $\delta$. In this connection we discuss two extreme
cases: the zero phase, $\delta = 0$, and the maximal CP-violation, $\delta =
\pm \pi/2$, and relate them to the peculiar pattern of the neutrino mixing. The
maximal CP-violation can be related to the $\nu_\mu - \nu_\tau$ reflection
symmetry. We study various aspects of this symmetry and introduce a generalized
reflection symmetry that can lead to an arbitrary phase that depends on the
parameter of the symmetry transformation. The generalized reflection symmetry
predicts a simple relation between the Dirac and Majorana phases. We also
consider the possibility of certain relations between the CP-violating phases
in the quark and lepton sectors.
