  One of the consequences of Cooper pairs having a finite momentum in the
interlayer of a Josephson junction, is $\pi$-junction behavior. The finite
momentum can either be due to an exchange field in ferromagnetic Josephson
junctions, or due to the Zeeman effect. Here, we report the observation of
Zeeman effect induced 0-$\pi$ transitions in Bi$_{1-x}$Sb$_x$, 3D Dirac
semimetal-based Josephson junctions. The large g-factor of the Zeeman effect
from a magnetic field applied in the plane of the junction allows tuning of the
Josephson junctions from 0- to $\pi$- regimes. This is revealed by sign changes
in the modulation of the critical current by applied magnetic field of an
asymmetric superconducting quantum interference device (SQUID). Additionally,
we directly measure a non-sinusoidal current-phase relation in the asymmetric
SQUID, consistent with models for ballistic Josephson transport.
