Field-parametrization dependence of Dirac's method for constrained   Hamiltonians with first-class constraints: failure or triumph? Non-covariant   models
  We argue that the field-parametrization dependence of Dirac's procedure, for Hamiltonians with first-class constraints not only preserves covariance in covariant theories, but in non-covariant gauge theories it allows one to find the natural field parametrization in which the Hamiltonian formulation automatically leads to the simplest gauge symmetry. 
N. Kiriushcheva, P.G. Komorowski, and S.V. Kuzmin
hep-th gr-qc