Английский словарь американских идиом - give the benefit of the doubt

{v. phr.} To believe (a person) is innocent rather than guilty when you are not sure. * /The money was stolen and John was the only boy who had known where it was, but the teacher gave him the benefit of the doubt./ * /George's grade was higher than usual and he might have cheated, but his teacher gave him the benefit of the doubt./