  We study the standard three-dimensional driven diffusive system on a simple
cubic lattice where particle jumps along a given lattice direction are biased
by an infinitely strong field, while those along other directions follow the
usual Kawasaki dynamics. Our goal is to determine which of the several existing
theories for critical behavior is valid. We analyze finite-size scaling
properties using a range of system shapes and sizes far exceeding previous
studies. Four different analytic predictions are tested against the numerical
data. Binder and Wang's prediction does not fit the data well. Among the two
slightly different versions of Leung, the one including the effects of a
dangerous irrelevant variable appears to be better. Recently proposed isotropic
finite-size scaling is inconsistent with our data from cubic systems, where
systematic deviations are found, especially in scaling at the critical
temperature.
