  We use deep HST STIS and NICMOS images of three spectroscopically confirmed
galaxy counterparts of high-redshift damped Ly-alpha (DLA) absorbers (one of
which is a new discovery) to test the hypothesis that high-redshift DLA
galaxies are Lyman-break galaxies. If this hypothesis is correct the emission
properties of DLA galaxies must lie within the range of emission properties
measured for Lyman-break galaxies of similar absolute magnitude. This will be
true regardless of selection biases in the sample of detected DLA galaxies. We
test this prediction using several emission properties: half-light radius,
radial profile (Sersic n parameter), optical-to-near-infrared colour,
morphology, Ly alpha emission equivalent width, and Ly alpha emission velocity
structure. In all cases the measured values for the DLA galaxies lie within the
range measured for the population of Lyman-break galaxies. None of the
measurements is in conflict with the prediction. We conclude that the measured
emission properties of the three DLA galaxies studied here are consistent with
the conjecture that high-redshift DLA galaxies are Lyman-break galaxies. We
show that this result does not conflict with the observation that the few
high-redshift DLA galaxies discovered are mostly fainter than spectroscopically
confirmed L* Lyman-break galaxies.
