  I briefly review the Gribov ambiguity of Yang-Mills theory, some of its
features and attempts to control it, in particular the Gribov-Zwanziger
proposal to restrict the functional integration in the Landau gauge to the
Gribov region. This proposal is extended to an arbitrary gauge in such a way as
to guarantee BRST invariance. The key insight is that any gauge change in the
generating functional can be effected by a suitable field-dependent BRST
transformation. I derive a simple analytic formula for the Jacobian of such a
transformation, which yields an explicit recipe for the required
transformation-parameter functional and allows for the computation of the
Gribov horizon functional in any gauge, as I illustrate for the class of R_xi
gauges.
