  In this paper we want to compare the theoretical predictions of a law
proposed by Feoli and Mancini, with the most recent experimental data about
galaxies and Supermassive black holes. The physical principle behind this law
is the transformation of the angular momentum of the interstellar material,
which falls into the black hole, into the angular momentum of the radiation
emitted in this process. Despite the simplicity of the model, this law shows an
excellent agreement with the experimental data for early-type galaxies while a
new approach is proposed for spirals.
