  We consider the problem of designing an Ansatz for the fermion-photon vertex
function, using three-dimensional quantum electrodynamics as a test case. In
many existing studies, restrictions have been placed on the form of the vertex
Ansatz by making the unsubstantiated assumption that in the quenched, massless
limit the Landau gauge Dyson-Schwinger equations admit a trivial solution. We
demonstrate, without recourse to this assumption, the existence of a non-local
gauge in which the fermion propagator is the bare propagator. This result is
used to provide a viable Ansatz for part of the vertex function.
