  Brian Pitts has recently claimed to show via straightforward calculation
that, at least in the case of Hamiltonian electromagnetism, an arbitrary
first-class constraint ``generates not a gauge transformation, but a bad
physical change'' (Annals of Physics 351 (2014) pp.382-406; arXiv:1310.2756).
We show, via a straightforward calculation, that a transformation generated by
an arbitrary first-class constraint relates gauge-equivalent phase space
points, vindicating orthodoxy. Pitts, however, is primarily concerned with
transformations of entire histories, rather than of instantaneous states. We
show that, even in this context, a transformation generated by an arbitrary
first-class constraint is also a gauge transformation, once the empirically
observed electric field is correctly identified via its dynamical interactions
with charge, and not simply given stipulatively as a certain combination of the
potential and its derivatives.
