benefit of the doubt, to give/have the

To assume or treat as innocent when there is conflicting evidence. The term comes from the law in many countries,  whereby  a  person  must  be  assumed  to  be  innocent  of  a  crime unless  definitely  proved  to  be  guilty; in  other  words, when  in  doubt, the verdict  must  be “not  guilty.” The  expression  began  to  be  used  figuratively for all kinds of situation in the nineteenth century.