  We prove a perturbative result concerning the uniqueness of Kerr-Newman
family of black holes: given an asymptotically flat space-time with bifurcate
horizons, if it agrees with a non-extremal Kerr-Newman space-time
asymptotically flat at infinity and it is sufficiently close to the Kerr-Newman
family, then the space-time must be one of the Kerr-Newman solutions. The
closeness to the Kerr-Newman family is measured by the smallness of a pair of
Mars-Simon type tensors, which were introduced by Wong in \cite{Wong_09} to
detect the Kerr-Newmann family.
