Given a dynamical unitary representation of rotations, U ( R ) , the product U 0 ( R ) U † † ( R ) of a kinematic rotation with the inverse of the corresponding dynamical rotation is a unitary operator that (1) preserves the S -matrix and (2) changes the kinematic subgroup to a kinematic subgroup with a rotated light front, n ^ ^ ′ = R n ^ ^ . Conversely, if the S -matrix is invariant with respect to changing the orientation of the light-front, then the dynamical unitary representation of rotations, U ( R ) , can be constructed using the generalized wave operators for different orientations of the light front and the kinematic representation of rotations