literally, blank document; see carte
Carte blanche entered the English language as a French loan word in the mid-17th century, when card games were all the rage. A highly fashionable game of the time was piquet, in which a carte blanche was a hand having no face cards. When not playing piquet, English speakers used carte blanche in a literal sense to refer to physical pieces of paper (“carte”) that were blank or white (“blanche”).
By the 18th century, the meaning had expanded to include blank pieces of paper upon which someone signed his name, trusting a second party to come up with the stipulations of a deal. This idea of signing a yet-unwritten contract and handing over authority to the other party led us to the sense most familiar to speakers of modern-day English. Nowadays, if someone has been given carte blanche, it does not mean that she is holding a blank contract or playing cards. It means that she is free to do or say whatever she pleases.
Note that it is a mistake to say “a carte blanche” unless you are talking about a piquet hand or a blank, signed contract. When used in the sense of giving someone free reign, you say they have been given “carte blanche,” and not “a carte blanche.”
On the other hand, blank check, an English term with very similar meanings, is always used with “a” or some other determiner. That term underwent the same progression as carte blanche from its literal meaning to a figurative one (as in Congress gave the president a blank check of unconditional support). Unlike carte blanche, however, the literal meaning has not fallen out of use. We no longer play piquet, but we still, occasionally, write checks.
—Carte Blanche: A painting by Belgian surrealist René Magritte. It depicts a horse and rider, apparently walking through a forest, though closer inspection shows the forest visible through the horse and rider. The painting is meant as a meditation on art and its relationship to reality.
—Carte Blanche: An album released by American hip-hop artist Phat Kat in the late 2000s.
—Carte Blanche: The 37th novel in the James Bond franchise, written by Jeffery Deaver.
“I understand that you give me carte blanche to act for you, provided only that I get back the gems, and that you would place no limit on the sum I may draw.“
—Sir Arthur Conan Doyle, “The Adventure of the Beryl Coronet“ Adventures of Sherlock Holmes (1892)
“[T]his deal gave the developer carte blanche to wield power in a self-interested way.“
—Steve France, “Dusty Doctrines“ ABA Journal (May 2001)
“It’s the kind of success which pretty much gives them carte blanche in terms of what they want to do next, although they’ve always done their own thing.“
—Adam Lowes, “‘Hornet’ Brings in the Green While True Grit Hangs in There“ HeyUGuys (January 18, 2011)