  Non-zero leptonic CP phases in the neutrino sector are clear evidence for
physics beyond the Standard Model and have many implications in particle
physics and cosmology. Some clues to maximal Dirac CP violation
$\delta_{CP}=3\pi/2$ are reviewed. An approach to connect the Dirac CP
violation phase and the neutrino mass hierarchy in terms of the measurement of
CP asymmetry is proposed. Under appropriate requirements for baseline distance
and beam energy, the problem of neutrino mass hierarchy can be revealed at
maximal Dirac CP violation. General allowed parameter spaces are investigated,
within which the two unknown neutrino issues, mass hierarchy and Dirac CP
violation, can be solved simultaneously. The abilities of addressing the mass
hierarchy of current long baseline neutrino experiments are also discussed.
