The Lion and the Mouse(1928)

Judge Ross, on the Federal Bench, rules in favor of a large company in litigation before him, unaware that a smaller company in which he owns considerable stock has been subsumed by the larger firm, thus creating the appearance of a conflict of interests. When one of the Judge's enemies plots to ruin the Judge over this apparent improper behavior, Judge Ross's daughter Shirley sets out to prove her father's innocence.