A longstanding effort by the town of Edgartown to protect five ancient byways suffered a setback last week when a superior court judge sent a district of critical planning concern (DCPC) designation back to the Martha’s Vineyard Commission for another review.

The five paths are Middle Line Road, Ben Tom’s Road, Pennywise Path, Watcha Path and Tar Kiln Road. Their use as cart paths and byways dates to Colonial times, and in 2007 the commission approved a town-sponsored initiative to designate them as special ways under the Island Road District DCPC.

But in a Feb. 11 ruling, the Hon. Cornelius Moriarty found that the commission had failed to make the required findings in two instances under its own regulations.

The highly technical ruling is on a single count in a complicated case brought against the commission by the Hall family of Edgartown which owns property along Ben Tom’s and Middle Line Roads. All other counts were dismissed.

Judge Moriarty has now sent the matter back to the commission for reconsideration within 30 days. The DCPC designation has been declared invalid although a building moratorium will remain in place.

“The MVC’s failure to make these findings cannot be dismissed as insignificant when the stakes are so high for landowners such as the plaintiffs . . . The MVC’s failure to make these finding constitutes an error of law,” Judge Moriarty wrote in the 20-page decision.

But the judge also found that the error of law was not so great as to warrant overturning the commission’s decision altogether.

“That is because the evidence in the administrative record could support findings that the five ways would not be adequately preserved without designating and regulating them as DCPCs, and that failure to develop properly the five ways may result in a substantial loss to the region,” the judge wrote.

In a statement last week, MVC executive director Mark London said the commission will rehear the DCPC.

“The commission’s intention has always been to protect the cultural and historical character of these ancient ways, and neither to grant public access where it does not presently exist, nor to deny the reasonable development of properties abutting these historic pathways,” Mr. London said. “The commission intends to reconsider this nomination . . . and expects to be able to deal with the concerns that have been raised.”

A public hearing will be held on March 10 at the commission office in the Olde Stone Building in Oak Bluffs.