[en] Two topics are presented. The first one is a novel approach for a Poincaré covariant description of nuclear dynamics based on light-front Hamiltonian dynamics. The key quantity is the light-front spectral function, where both normalization and momentum sum rule can be satisfied at the same time. Preliminary results are discussed for an initial analysis of the role of relativity in the EMC effect in "3He. A second issue, very challenging, is considered in a non-relativistic framework, namely a distorted spin-dependent spectral function for "3He in order to take care of the final state interaction between the observed pion and the remnant in semi-inclusive deep inelastic electron scattering off polarized "3He. The generalization of the analysis within the light-front dynamics is outlined. (author)