  A new set of projection operators for three-dimensional models are
constructed. Using these operators, an uncomplicated and easily handling
algorithm for analysing the unitarity of the aforementioned systems is built
up. Interestingly enough, this method converts the task of probing the
unitarity of a given 3D system, that is in general a time-consuming work, into
a straightforward algebraic exercise; besides, it also greatly clarifies the
physical interpretation of the propagating modes. In order to test the efficacy
and quickness of the algorithm at hand, the unitarity of some important and
timely higher-order electromagnetic (gravitational) systems augmented by both
Chern-Simons and higher order Chern-Simons terms are investigated.
