  The standard approach to Higgs mechanism is based on the existence of unitary
gauge but, unfortunately, it does not come from a coordinate change in the
configuration space of the initial model and actually defines a new dynamical
system. So, it is a questionable approach to the problem but it is shown here
that the final result could still make sense as a Marsden-Weinstein reduced
system. (This reduction can be seen as completely analogous to the procedure of
obtaining the "centrifugal" potential in the classical Kepler problem.) It is
shown that in the standard linearization approximation of the Coulomb gauged
Higgs model geometrical constraint theory offers an explanation of the Higgs
mechanism because solving of the Gauss law constraint leads to different
physical submanifolds which are not preserved by the action of the (broken)
global U(1) group.
