  The Observed Perlmutter-Riess Acceleration (OPRA) implies that the expansion
of the Universe is currently increasing and is motivation for the so-called
phantom energy models. We consider the dynamics of phantom scalar field models.
An important physical time constraint, which can be used to rule out many
cosmological models, is obtained from the condition that all forms of energy
density, including the field causing OPRA (e.g., the phantom field), must be
non-negligible for an extended period, which is conservatively estimated to be
of the order of a few $Gyr$. We find that this physical time constraint cannot
be satisfied in conventional phantom cosmological models.
