  Leakage is a particularly damaging error that occurs when a qubit state falls
out of its two-level computational subspace. Compared to independent
depolarizing noise, leaked qubits may produce many more configurations of
harmful correlated errors during error-correction. In this work, we investigate
different local codes in the low-error regime of a leakage gate error model.
When restricting to bare-ancilla extraction, we observe that subsystem codes
are good candidates for handling leakage, as their locality can limit damaging
correlated errors. As a case study, we compare subspace surface codes to the
subsystem surface codes introduced by Bravyi et al. In contrast to depolarizing
noise, subsystem surface codes outperform same-distance subspace surface codes
below error rates as high as $\lessapprox 7.5 \times 10^{-4}$ while offering
better per-qubit distance protection. Furthermore, we show that at low to
intermediate distances, Bacon-Shor codes offer better per-qubit error
protection against leakage in an ion-trap motivated error model below error
rates as high as $\lessapprox 1.2 \times 10^{-3}$. For restricted leakage
models, this advantage can be extended to higher distances by relaxing to
unverified two-qubit cat state extraction in the surface code. These results
highlight an intrinsic benefit of subsystem code locality to error-corrective
performance.
