Borrowing from French , referring to a "blank card". carte blanche
( carte blanche plural ) cartes blanches
Unlimited discretionary power to act; unrestricted authority.
: 1910, Emerson Hough, chapter 1, The Purchase Price
“[…] But since when did army officers afford the luxury of amanuenses in this simple republic ? [… ] Does your carte blanche run so far as that also ?”
2012 May 15, Scott Tobias, “ Film: Reviews: The Dictator”, The Onion AV Club:
Baron Cohen and director Larry Charles have indeed retreated with The Dictator, but they’ve gone back 80 years, when the Marx Brothers were given carte blanche at Paramount Pictures with a five-movie run that ended with their best movie, 1933’s Duck Soup.
2001, Oliver Sacks, , Uncle Tungsten: Memories of a Chemical Boyhood Alfred A. Knopf (2001), 15,
Indeed, I later learned that when they had bought the place, in 1930, they had given my father's older sister Lina their checkbook,
carte blanche, saying, "Do what you want, get what you want.