  Measuring the polarization of the prompt gamma-ray emission from GRBs can
significantly improve our understanding of both the GRB emission mechanisms, as
well as the underlying engine driving the explosion. We searched for
polarization in the prompt gamma-ray emission of GRB 041219a with the SPI
instrument on INTEGRAL. Using multiple-detector coincidence events in the
100--350 keV energy band, our analysis yields a polarization fraction from this
GRB of 99 +- 33 %. Statistically, we cannot claim a polarization detection from
this source. Moreover, different event selection criteria lead to even less
significant polarization fractions, e.g. lower polarization fractions are
obtained when higher energies are included in the analysis. We cannot strongly
rule out the possibility that the measured modulation is dominated by
instrumental systematics. Therefore, SPI observations of GRB 041219a do not
significantly constrain GRB models. However, this measurement demonstrates the
capability of SPI to measure polarization, and the techniques developed for
this analysis.
