  We introduce an effective field theory approach that describes the motion of
finite size objects under the influence of electromagnetic fields. We prove
that leading order effects due to the finite radius $R$ of a spherically
symmetric charge is order $R^2$ rather than order $R$ in any physical model, as
widely claimed in the literature. This scaling arises as a consequence of
Poincar\'e and gauge symmetries, which can be shown to exclude linear
corrections. We use the formalism to calculate the leading order finite size
correction to the Abraham-Lorentz-Dirac force.
