We present a fully relativistic and gauge invariant framework for calculating the cross-sections of dilepton production in nucleon–nucleon ($N N$) collisions which is based on the meson-exchange approximation for the $N N$ scattering amplitudes. Predictions of our model are compared with those of other covariant models that have been used to describe this reaction. We discuss the comparison of our calculations with the old DLS and the recent HADES data.
