Having been a victim of plagiarism by established researchers long time ago, I think that clear anti-plagiarism policies and procedures / sanctions that are strictly enforced are absolutely necessary at the institution level. The problem with established researchers might be smaller in terms of volume but probably more important - it might allow career advancement of potentially incompetent people that might be able to get senior academic positions. It is sometimes overlooked compared with plagiarism by students. I think it deserves equal - or even more - attention.