  Inspired by the work of Pratt and coworkers on a sum rule for the
polarization correlations in electron bremsstrahlung when the outgoing electron
is not observed, we derive the corresponding sum rule for the elementary
process of bremsstrahlung. This sum rule is valid for arbitrary electron
wavefunctions provided the electron is emitted in the reaction plane. The
numerical evaluation of this sum rule within the Dirac partial-wave theory for
bare inert spin-zero nuclei and collision energies in the range of 1-10 MeV
reveals violations for high nuclear charge. Such violations serve as a measure
of the inaccuracies in the bremsstrahlung calculations.
