I think it was after Clinton and the blue dress, but the statute changed. It's no longer called "independent counsel" it is now "special counsel" and apparently watered down. The nomenclature - and what we're seeing - sure points out there is nothing independent about the role and the use special treatment of some is clear.
Interesting history about OIC here:
https://www.pbs.org/wgbh/pages/frontline/shows/counsel/office/history.html