[AZLiberty]

According to the Online Etymology Dictionary, the first known use of the word "undercover" to mean "operating secretly" was 1920.

I call anachronism on this Benjamin Rush thing.

[Steve Van Doorn]

Actual Quote
"The Constitution of this Republic should make special provision for medical freedom. To restrict the art of healing to one class will constitute the Bastille of medical science. All such laws are un-American and despotic. ... Unless we put medical freedom into the constitution the time will come when medicine will organize into an undercover dictatorship and force people who wish doctors and treatment of their own choice to submit to only what the dictating outfit offers."
https://books.google.com/books?id=QnITAQAAMAAJ&pg=PA51#v=onepage&q&f=false

[Steve Van Doorn]

Not sure my last post was correct either. I didn’t find it in the book. The term in those days would be under-board. undercover does seem like a more modern term.