Ehrenfest theorem is proven in relativistic quantum theory of charged
particles, moving under the influence of an external electromagnetic field. In
order to extend the classic Ehrenfest result to the relativistic domain we
bypassed the problems with the relativistic position operator by deriving
directly Newton's second law. Our approach is characterized by its
universality. The detailed form of the wave equation is not needed. All that is
required is the existence of the conserved electric four-current built from the
particle wave function. The derivation is based on the conservation laws for
the energy and momentum.