delivered the opinion of the Court:.

The police court has undoubted jurisdiction in this as in all cases of prosecution for the violation of the municipal regulations.

“A writ of prohibition is never to be issued unless it clearly appears that the inferior court is about to exceed its jurisdiction. It cannot be made to serve the purpose of a writ of error or certiorari to correct mistakes of that court in deciding any question of law and fact within its jurisdiction.” Smith v. Whitney, 116 U. S. 167, 176, 29 L. ed. 601, 604, 6 Sup. Ct. Rep. 570.

Whether the invalidity of a regulation about to be enforced in that court presents such a case of excess of jurisdiction as; would justify the issue of the writ presents a question of difficulty which the exigency of the present case does not require-us to determine. The validity of the regulation is a question of law which the police court must necessarily determine in the exercise of its jurisdiction of the' subject-matter. If decided adversely to the petitioner, and his conviction follows, he may apply for a writ of error to review the judgment. The petitioner, having been prosecuted in one case only, cannot be seriously injured by leaving him to bring his case before this court,, if occasion shall require, in the ordinary course.

As there seems to be some doubt of the authority of the commissioners to enact the new regulation providing a penalty for the failure to remove snow and ice from the sidewalks of the city of Washington, and the question is one of general importance-to householders, the suspension of trials for the infraction of the-regulation until that question can be finally determined would probably relieve the hardship of the situation without injury to-the interests of the public or of individuals. For the reasons, given, the writ prayed for is refused and the petition dismissed, with costs.