  A new spinning particle with a definite sign of the energy is defined on
spacelike hypersurfaces after a critical discussion of the standard spinning
particles. They are the pseudoclassical basis of the positive energy $({1\over
2},0)$ [or negative energy $(0,{1\over 2})$] parts of the $({1\over 2},{1\over
2})$ solutions of the Dirac equation. The study of the isolated system of N
such spinning charged particles plus the electromagnetic field leads to their
description in the rest-frame Wigner-covariant instant form of dynamics on the
Wigner hyperplanes orthogonal to the total 4-momentum of the isolated system
(when it is timelike). We find that on such hyperplanes these spinning
particles have a nonminimal coupling only of the type "spin-magnetic field"
like the nonrelativistic Pauli particles to which they tend in the
nonrelativistic limit. The Lienard-Wiechert potentials associated with these
charged spinning particles are found. Then, a comment on how to quantize the
spinning particles respecting their fibered structure describing the spin
structure is done.
