give someone the benefit of the doubt
give (someone or something) the benefit of the doubt
To retain a favorable or at least neutral opinion of someone or something until the full information about the subject is available. You're my sister! Can't you give me the benefit of the doubt, instead of believing the worst about me right away? Let's give him the benefit of the doubt before we start accusing him. There may be a good explanation for the missing money.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
give someone the benefit of the doubt
COMMON
1. If you give someone the benefit of the doubt, you decide to believe that what they are saying is honest, even though it is possible that they are not telling the truth. As to whether she deliberately lied or got the facts wrong, I suppose we could give her the benefit of the doubt.
2. If you give someone the benefit of the doubt, you decide to believe that what they are doing is right, even though it is possible that they are doing something wrong. I am basically a trusting person. I make it a practice to give everyone the benefit of the doubt.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012