  The spectral energy distributions (SEDs) of some blazars exhibit an
ultraviolet (UV) and/or soft X-ray excess, which can be modelled with different
radiation mechanisms. Polarization measurements of the UV/X-ray emission from
blazars may provide new and unique information about the astrophysical
environment of blazar jets, and could thus help to distinguish between
different emission scenarios. In this paper, a new Monte-Carlo code -- MAPPIES
(Monte-Carlo Applications for Partially Polarized Inverse External-Compton
Scattering) -- for polarization-dependent Compton scattering is used to
simulate the polarization signatures in a model where the UV/soft X-ray excess
arises from the bulk Compton process. Predictions of the expected polarization
signatures of Compton emission from the soft X-ray excess in the SED of AO
0235+164, and the UV excess in the SED of 3C 279 are made for upcoming and
proposed polarimetry missions.
