give someone free rein
give (one) free rein
To give one complete freedom to do what one wants or chooses. "Rein" refers to the reins of a horse. Can you believe the boss gave me free rein on this project? Finally, I can present a campaign with my own vision!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
give someone free reinor
give someone a free rein
COMMON If you give someone free rein or give someone a free rein, you give them all the freedom they want or need to do something. Note: The reference in these expressions is to a rider using the reins to control a horse. He was given free rein to manage the project as he wished. Much to her delight, she was given a free rein to decorate the house exactly as she wanted. Note: You can also say that you allow someone free reign. The artists were allowed free rein to produce what they thought fitted the space. Note: You can also say that you have free rein. The children have free rein to choose the subjects that they want to study.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012