  The in-plane magnetic field suppresses the quantum coupling between electrons
in a double quantum well structure. The microscopical theory of this effect is
developed and confirmed experimentally. We have shown that the decrease of the
"resistance resonance" peak is sensitive to the mutual orientation of the
current and the in-plane magnetic field. The characteristic field required for
the suppression of the resonance depends on the elastic small angle and
electron--electron scattering rates. The study of the characteristic field
allows to verify the temperature and Fermi energy dependence of the
electron--electron scattering rate, providing a new experimental tool for its
measurement.
