12.12. For the duration of a strike or a lock-out declared in accordance with this Act, the employer is prohibited from(a) utilizing the services of a person, hired between the beginning of the negotiation stage and the end of the strike or lock-out, to discharge the duties of an attorney represented by the association;
(b) utilizing the services of an attorney represented by the association, except to the extent provided for in an agreement or a list approved by the Commission des relations du travail.