wow, thanks, I had never heard of Campbell's law, and it really puts into a concise form what I believe about a lot of things (from science publishing to interest rate manipulation).
I think i originally ran into a British variant, called Goodheart's Law, while reading about reforms to their National Health Service.
https://en.wikipedia.org/wiki/Goodhart's_law
The particular example being of how hospitals where given a negative rating based on how many patients were left waiting on stretchers (the rating system being introduced in an attempt at producing market like forces within the NHS). To get around this, the staff started removing the wheels on the stretchers while the patient was waiting. That way it was a bed, not a stretcher...
All this runs smack into Cambell's law.
https://en.wikipedia.org/wiki/Campbell's_law