carte blanche  (kärt bläsh, blänch, blnch)​

n. pl. cartes blanches (kärt bläsh, kärts blänch, blnch)

Unrestricted power to act at one's own discretion; unconditional authority:                                                                                                       

     gave the designer carte blanche to modernize the summer home.

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[French : carte, ticket + blanche, blank.]