  We present a modified inertia formulation of Modified Newtonian dynamics
(MOND) without retaining Galilean invariance. Assuming that the existence of a
universal upper bound, predicted by MOND, to the acceleration produced by a
dark halo is equivalent to a violation of the hypothesis of locality (which
states that an accelerated observer is pointwise inertial), we demonstrate that
Milgrom's law is invariant under a new space-time coordinate transformation. In
light of the new coordinate symmetry, we address the deficiency of MOND in
resolving the mass discrepancy problem in clusters of galaxies.
