Plea for act done under warrant

When any civil suit or prosecution against a police officer has been instituted for any act done by him in the capacity of a police officer, he may plead that such act was done by him in pursuance of a warrant issued by a Magistrate. Such plea shall be proved by the production of the warrant directing to do such act and puporting to be signed by such Magistrate. The defendant shall, on the production of such warrant, be entitled to receive a decree in his favour notwithstanding a defect of jurisdiction in such Magistrate. No proof of the signature of such Magistrate shall be necessary unless the Court has reason to doubt its being genuine: Provided that nothing contained in this section shall effect the remedy of the plaintiff which he may have against the authority issuing the warrant.