give the benefit of the doubt
Regard someone as innocent until proven otherwise; lean toward a favorable view of someone. For example, Let's give her the benefit of the doubt and assume that she's right. [Mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.