  Following the recent NMR experiments by Gorny et al., we discuss the effect
of a magnetic field on the superconducting T_c and the spin pseudo-gap T^*. As
a testable prediction, we argue that a spin pseudo-gap should also be observed
in over-doped samples in a magnetic fied (while normally there is no pseudo-gap
above T_c). We find that different theoretical approaches have marked
differences in their predictions for over-doped HTc cuprates.
