Give somebody the benefit of the doubt
Definition 1 of 1
Pro Tip 1/3Trust Choice
Use when you choose to trust someone despite doubts or lack of proof. 
I wasn't sure if he was telling the truth, but I gave him the benefit of the doubt.
Pro Tip 2/3Uncertain Situation
Apply it when the truth is uncertain and you're leaning towards a positive judgment. 
The witness's story had some holes, but the jury gave him the benefit of the doubt.
Pro Tip 3/3Positive Assumption
It leans towards making a positive assumption about someone's actions or motives. 
His alibi was shaky, but I decided to give him the benefit of the doubt.