  The current paper is dedicated to determining perturbative expansions for
Lagrangians describing classical, relativistic, pointlike particles subject to
Lorentz violation parameterized by the nonminimal Standard-Model Extension
(SME). An iterative technique recently developed and applied to a
Lorentz-violating scalar field theory is now adopted to treat the
spin-degenerate SME fermion sector. Lagrangians are obtained at third order in
Lorentz violation for the operators $\hat{a}_{\mu}$, $\hat{c}_{\mu}$,
$\hat{e}$, $\hat{f}$, and $\hat{m}$ for arbitrary mass dimension. The results
demonstrate the impact of nonzero spin on classical particle propagation. They
will be useful for phenomenological studies of modified gravity and could
provide useful insights into explicit Lorentz violation in curved spacetimes.
