13.—(1) An action against a trade union, whether of workers or employers, or its trustees or against any members or officials thereof on behalf of themselves and all other members of the trade union in respect of any tortious act committed by or on behalf of the trade union in contemplation or furtherance of a trade dispute, shall not be entertained by any court.

(2) In an action against any trade union or person referred to in subsection (1) in respect of any tortious act alleged or found to have been committed by or on behalf of a trade union it shall be a defence that the act was done in the reasonable belief that it was done in contemplation or furtherance of a trade dispute.