RSA 277:25: Petition.

Any employer affected by such order, rule or regulation may petition the commissioner for a review of the validity or reasonableness thereof. The commissioner may join in one proceeding all petitions alleging invalidity or unreasonableness of the same or substantially similar orders, rules or regulations. The petition for review shall be filed within 30 days after notice of the adoption of the order, rule or regulation; provided, that the commissioner may, whenever in his opinion justice may require it, extend the time for filing such petition.