Verb
hold the reins (third-person singular simple present holds the reins, present participle holding the reins, simple past and past participle held the reins)
(idiomatic) To be in charge, to be in control, as of a business, political organization, or other group.
If passion drives you, let reason hold the reins. Benjamin Franklin
For there is no constitutional right for any race to be preferred... If discrimination based on race is constitutionally permissible when those who hold the reins can come up with "compelling" reasons to justify it, then constitutional guarantees acquire an accordion-like quality. William O. Douglas
If passion drives, let reason hold the reins. American Proverb