Normal forms and gauge symmetries of local dynamics
  A systematic procedure is proposed for deriving all the gauge symmetries of the general, not necessarily variational, equations of motion. For the variational equations, this procedure reduces to the Dirac-Bergmann algorithm for the constrained Hamiltonian systems with certain extension: it remains applicable beyond the scope of Dirac's conjecture. Even though no pairing exists between the constraints and the gauge symmetry generators in general non-variational dynamics, certain counterparts still can be identified of the first- and second-class constraints without appealing to any Poisson structure. It is shown that the general local gauge dynamics can be equivalently reformulated in the involutive normal form. The last form of dynamics always admits the BRST embedding, which does not require the classical equations to follow from any variational principle. 
S.L. Lyakhovich and A.A. Sharapov