No officer or member of any association or organization, and no association or organization participating or interested in a labor dispute as herein defined, shall be held responsible or liable in any civil action at law or suit in equity or in any criminal prosecution for the unlawful acts of individual officers, members or agents, except upon proof beyond a reasonable doubt in criminal cases, and by the weight of evidence in other cases, and without the aid of any presumptions of law or fact, both of--(a) the doing of such acts by persons who are officers, members or agents of any such association or organization; and (b) actual participation in, or actual authorization of, such acts, or of ratification of such acts after actual knowledge thereof by such association or organization.