Section 6C. Any person aggrieved by the disapproval of a project by a hearing authority, or by disapproval of a project by the mayor or the selectmen or by the approval or disapproval of a project by the housing board, or by the failure of any of them to act within the time required by section six may appeal to the superior court of the county where the proposed project is to be located by filing a complaint within sixty days after the transmittal of the report of the city council or in the case of towns, the planning board, or after the issuance of the certificate evidencing approval or disapproval by the mayor or selectmen, or after the certificate or objections of the housing board are issued. Where any of them have failed to act within the time required by section six, the complaint must be filed within thirty days after the last day of the time allowed for such action by section six. The complaint shall allege the specific respects in which the action of the hearing authority, or the mayor or selectmen, or the housing board is based upon error of law or is unsupported by substantial evidence, or is without authority and a copy of the report of the planning board, or the mayor or selectmen, or a copy of the certificate or objections of the housing board shall be attached to the complaint. A complaint alleging delay beyond the time allowed by section six shall set forth the dates the application or report was filed or transmitted, the date by which action was required by section six, and that no action has been taken as of the date the complaint is filed.

A complaint filed by a person other than the applicant shall name the applicant and the hearing authorities as defendants.

Rule Four of the Massachusetts Rules of Civil Procedure shall not apply to cases under this section, and the complaint shall be served on each defendant by certified mail or delivery within seven days of the filing, and attached to the complaint filed in the superior court shall be a sworn certificate of service. No answers shall be required, but answers may be filed and served on all parties within twenty days of the date of service of the complaint. The court in its discretion may permit any person to intervene, but the court shall consider whether intervention will delay its review or prejudice the rights of any party. The clerk of the court shall give notice of all hearings in a case to all parties of record, whether or not they have filed answers or other pleadings.

The filing of a complaint under this section shall not stay an approval of a project by the housing board, but the court in its discretion may order a stay.

If the court finds that the decision under review is based upon an error of law or is not supported by substantial evidence or is without authority, the court shall reverse the decision or remand the matter for further proceedings. The court shall order the completion of any action unlawfully delayed. If the court finds that the decision under review is not based upon an error of law and is supported by substantial evidence, the court shall enter judgment accordingly.

As used in this section, hearing authority shall mean the planning board and city council in cities and planning board or selectmen when acting as the planning board in towns.

The remedy granted in this section shall be exclusive. No defect of procedure under section six or of notice under section six B shall be reviewed by a court except as provided in this section.

All proceedings under this section shall be placed before other civil matters on the calendar of the court.