  We discuss the precision determination of the leptonic Dirac CP phase
$\delta_{CP}$ in neutrino oscillation experiments, where we apply the concept
of ``CP coverage''. We demonstrate that this approach carries more information
than a conventional CP violation measurement, since it also describes the
exclusion of parameter regions. This will be very useful for next-generation
long baseline experiments where for sizable $\sin^2 2 \theta_{13}$ first
constraints on $\delta_{CP}$ can be obtained. As the most sophisticated
experimental setup, we analyze neutrino factories, where we illustrate the
major difficulties in their analysis. In addition, we compare their potential
to the one of superbeam upgrades and next-generation experiments, which also
includes a discussion of synergy effects. We find a strong dependence on the
yet unknown true values of $\sin^2 2 \theta_{13}$ and $\delta_{CP}$, as well as
a strong, non-Gaussian dependence on the confidence level. A systematic
understanding of the complicated parameter dependence will be given. In
addition, it is shown that comparisons of experiments and synergy discussions
do in general not allow for an unbiased judgment if they are only performed at
selected points in parameter space. Therefore, we present our results in
dependence of the yet unknown true values of $\sin^2 2 \theta_{13}$ and
$\delta_{CP}$. Finally we show that for $\delta_{CP}$ precision measurements
there exist simple strategies including superbeams, reactor experiments,
superbeam upgrades, and neutrino factories, where the crucial discriminator is
$\sin^2 2 \theta_{13} \sim 10^{-2}$.

High Energy Physics - Phenomenology