  We consider the factorization method in the spontaneously broken gauge
theories such as the electroweak theory. Using the of\/f-shell $W$-boson
density matrix formalism we demonstrate that the factorization conditions are
completely under control. The main point of this paper is the presence of the
"interference" or "crossed" terms in $WW$--scattering process which exhibits
itself in the dependence on the relative azimuthal angle between two scattering
planes. To illustrate our general consideration we use well-known example --- a
single Higgs boson production. The origine of the quantitative failure of the
$WW$--ef\/fective method, as originally propossed, is given and it is shown how
to use it correctly.
