  Classical electromagnetism with magnetic monopoles is not a Hamiltonian field
theory because the Jacobi identity for the Poisson bracket fails. The Jacobi
identity is recovered only if all of the species have the same ratio of
electric to magnetic charge or if an electron and a monopole can never collide.
Without the Jacobi identity, there are no local canonical coordinates or
Lagrangian action principle. To build a quantum theory of magnetic monopoles,
we either must explain why the positions of electrons and monopoles can never
coincide or we must resort to new quantization techniques.
