  We propose in this paper an effective low-energy theory for interacting
fermion systems which supports exclusion statistics. The theory can be viewed
as an extension of Landau Fermi liquid theory where besides quasi-particle
energy $\xi_{\mathbf{k}}$, the kinetic momentum $\mathbf{k}$ of quasi-particles
depends also on quasi-particle occupation numbers as a result of momentum
($k$)-dependent current-current interaction. The dependence of kinetic momentum
on quasi-particles excitations leads to change in density of states and
exclusion statistics. The properties of this new Fermi liquid state is studied
where we show that the state (which we call $U(1)$-Fermi liquid state) has
Fermi-liquid like properties except that the quasi-particles are {\em not}
adiabatically connected to bare fermions in the system and the state may not
satisfy Luttinger theorem.
