  Double beta decay has been proven to be a powerful tool to constrain $B-L$
violating physics beyond the standard model. We present a representation for
the long-range part of the general $0\nu\beta\beta$ decay rate allowed by
Lorentz-invariance. Combined with the short range part this general
parametrization in terms of effective $B-L$ violating couplings will provide
the $0\nu\beta\beta$ limits on arbitrary lepton number violating theories.
