Closing the book on a decades-long court battle over whether a private expanse of land off Moshup Trail can be opened up for development, the U.S. Supreme Court this week declined to hear the Decoulos-Kitras case in Aquinnah.

James Decoulos and Maria Kitras had petitioned the nation’s highest court to take their case on appeal, after the Massachusetts Supreme Judicial Court in the spring found they did not have legal access to two landlocked parcels totalling about 30 acres off Moshup Trail.

On Nov. 28 the petition was denied.

“It’s the end of a chapter,” said longtime Aquinnah town counsel Ronald H. Rappaport this week. Reached by telephone at his office in Belmont, Mr. Decoulos said the decision came as no surprise. “There was not a huge national issue here for the court to decide,” he said, adding: “We’re not done. We’re going to continue to fight for our rights that we believe we have under the constitution.”

The complicated land-use case dates to the late 1990s and had pitted Mr. Decoulos and his wife Ms. Kitras against the town of Aquinnah, the Vineyard Conservation Society and others. VCS has been involved for many years in a conservation initiative to protect the salt-blasted Moshup Trail heathlands, which are considered globally rare.

The case could have had far-reaching effects on land titles throughout Aquinnah, and involved arcane issues of law, some dating to the late 19th century when most of the land in the town was owned in common by members of the Wampanoag Tribe of Gay Head.

The case bounced around in state courts for years, finally landing before the SJC last year. In a 25-page ruling issued in April, the court agreed with an earlier ruling by the land court that the plaintiffs could not prove legal access to their land.

In September, attorneys for Mr. Decoulos and Ms. Kitras formally petitioned the U.S. Supreme Court for a writ of certiorari. The town and other defendants in the case, including Caroline Kennedy and her husband Edwin Schlossberg, waived their right to respond.

VCS executive director Brendan O’Neill called the denial “a procedural end point for which we are grateful. Much credit goes to the town, the organizations and individuals whose commitment never flagged during these many years.” He concluded:

“The 20 years of legal defense speaks to the importance of watchfulness and tenacity and commitment over the long haul with respect to land protection issues like this one. And in the context of the unimaginable antiquity of the place we are trying to conserve — with its 50 million-year-old cretaceous soils — it’s a blink of an eye.”