  We investigate the static and dynamic critical behaviour of a uniformly
driven bilayer Ising lattice gas at half filling. Depending on the strength of
the interlayer coupling J, phase separation occurs across or within the two
layers. The former transitions are controlled by the universality class of
model A (corresponding to an Ising model with Glauber dynamics), with upper
critical dimension d_c=4. The latter transitions are dominated by the
universality class of the standard (single-layer) driven Ising lattice gas,
with d_c=5 and a non-classical anisotropy exponent. These two distinct critical
lines meet at a non-equilibrium bicritical point which also falls into the
driven Ising class. At all transitions, novel couplings and dangerous
irrelevant operators determine corrections to scaling.
