  We study the problem of covariant separation between first and second class
constraints for the $D=10$ Brink-Schwarz superparticle. Opposite to the
supersymmetric light-cone frame separation, we show here that there is a
Lorentz covariant way to identify the second class constraints such that,
however, supersymmetry is broken. Consequences for the $D=10$ superstring are
briefly discussed.
