  The CKM paradigm has been tested thoroughly over the last 40 years in both
the neutral $K$ and $B$ systems. The recent discovery of neutral charm meson
mixing has prompted the search for CP violation in $D$ decays. We discuss the
prospects of performing time-dependent CP asymmetry measurements at facilities
either taking data or under construction. Such measurements can (i) provide
precision determinations of the charm mixing phase, and (ii) be used to probe
for possible new physics effects (and perhaps ultimately constrain the CKM
paradigm). We propose the use of the time-dependent asymmetry measurement of
$D^0 \to K^+K^-$ decays to measure the phase of charm mixing, where existing
experiments that are either under construction or taking data should be able to
reach a precision of $<1.5^\circ$, and to use the phase difference between $D^0
\to K^+K^-$ and $D^0 \to \pi^+\pi^-$ decays to constrain the angle $\beta_c$ of
the $cu$ unitarity triangle up to theoretical uncertainties from long distance
and loop contributions. A large phase difference measured between these modes
would indicate new physics.
