At University of California, San Diego, we require a brief training session for
reference librarians in which they learn about verification and tagging of
subject headings and then they are allowed to add relevant subject headings.
(This is called the Enhanced Access Program).  There are only a few who
actually do this, all of whom working in specialized areas (chemistry,
oceanography, latin american studies).  The system doesn't restrict them from
making other changes once they have authorization, but we've never had a
problem with them doing so.  (We do not give anyone outside of tech services
authorization to delete records or change holdings).

[Crystal Graham <Crystal_Graham@UCSDLIBRARY.UCSD.EDU>]