  We present the quantum critical theory of an interacting nodal Fermi-liquid
of quasi-relativisitc pseudo-spin-3/2 fermions that have a non-interacting
birefringent spectrum with two distinct Fermi velocities. When such
quasiparticles interact with gapless bosonic degrees of freedom that mediate
either the long-range Coulomb interaction or its short range component
(responsible for spontaneous symmetry breaking), in the deep infrared or
quantum critical regime in two dimensions the system is respectively described
by a marginal- or a non-Fermi liquid of relativistic spin-1/2 fermions
(possessing a unique velocity), and is always a marginal Fermi liquid in three
dimensions. We consider a possible generalization of these scenarios to
fermions with an arbitrary half-odd-integer spin, and conjecture that critical
spin-1/2 excitations represent a superuniversal description of the entire
family of interacting quasi-relativistic fermions.
