  We show that at electronic filling factor $\nu=1/2$, the lowest Landau level
constraint implies that at any temperature, and in the presence of {\it any}
amount of particle-hole symmetric disorder, the {\it composite fermion} Hall
conductivity is precisely $-e^2/2h$. (The electronic Hall conductivity is
$e^2/2h$.) This is inconsistent with the response of a composite Fermi liquid
in {\it zero} effective magnetic field. We also examine perturbatively the
nature of the putative composite Fermi liquid in the case in which the bare
particles are anyons with ``nearly'' Fermi statistics.
