  The Rastall's theory is a modification of General Relativity touching one of
the cornestone of gravity theory: the conservation laws. In Rastall's theory,
the energy-momentum tensor is not conserved anymore, depending now on the
gradient of the Ricci curvature. In this sense, this theory can be seen as a
classical implementation of quantum effects in a curved background space-time.
We exploit this structure in order to reproduce some results of an effective
theory of quantum loop cosmology. Later, we propose a model for the dark sector
of the universe. In this case, the corresponding $\Lambda$CDM model appears as
the only model consistent with observational data.
