it means that essentially the corrections officer union has gummed up any and all reforms passed through legislation (think video cameras in public areas, anti-violence training, etc.). this has led to a situation where there is a preventable suicide about once every 2 weeks in the prison and state officials are calling for federal intervention since they can't effectively change conditions; https://www.nydailynews.com/new-york/nyc-crime/ny-man-dies-r...
Oversight could easily mean installing surveillance infrastructure to monitor guards as well as inmates. Making that public would offer even more accountability.