  Although not designed primarily as a polarimeter, the \textit{Fermi}-Large
Area Telescope (LAT) has the potential to detect high degrees of linear
polarization from some of the brightest gamma-ray sources. To achieve the
needed accuracy in the reconstruction of the event geometry, low-energy
($\leq200$ MeV) events converting in the silicon detector layers of the LAT
tracker have to be used. We present preliminary results of the ongoing effort
within the LAT collaboration to measure gamma-ray polarization. We discuss the
statistical and systematic uncertainties affecting such a measurement. We show
that a $5\sigma$ minimum detectable polarization (MDP) of $\approx30-50\%$
could be within reach for the brightest gamma-ray sources as the Vela and Crab
pulsars and the blazar 3C 454.3, after 10 years of observation. To estimate the
systematic uncertainties, we stack bright AGN, and use this stack as a test
source. LAT sensitivity to polarization is estimated comparing the data to a
simulation of the expected unpolarized emission of the stack. We measure a
5$\sigma$ sensitivity limit corresponding to a polarization degree of
$\approx37\%$. This is in agreement with a purely statistical estimate,
suggesting that the systematic errors are likely to be small compared to the
statistical ones.
