18. Notwithstanding anything contained in any other law for the time being in force, an agreement between the members of a registered Trade Union shall not be void or voidable merely by reason of the fact that any of the objects of the agreement are in restraint of trade:
Provided that nothing in this section shall enable any civil court to entertain any legal proceedings instituted for the purpose of enforcing or recovering damages for the breach of any agreement concerning the conditions on which any members of a Trade Union shall or shall not sell their goods, transact business, work, employ or be employed.