31. Where an offence is ascertained by a peace officer or by a person entrusted with supervising the application of a statute of Québec or a regulation made thereunder, the justice of the peace may accept, in lieu of evidence of the person who ascertained the offence, a report signed by such person in the form approved by the Government. However, the accused may require such person to attend the hearing but the justice of the peace, if he finds the accused guilty, may condemn him to pay additional costs in an amount which he shall fix if he is of opinion that the submission of the report alone would have been sufficient.