carte blanche 
(kärt bläɴsh, blänch, blănch)
(kärt bläɴsh, blänch, blănch)n. pl. cartes blanches (kärt bläɴsh, kärts blänch, blănch)
Unrestricted power to act at one's own discretion; unconditional authority: gave the contractor carte blanche to modernize the kitchen.
[French : carte, ticket + blanche, blank.]