Construction of a massive observatory can proceed on one of the Native Hawaiian peoples’ most sacred sites, the Hawaii Supreme Court ruled on Tuesday in a major decision ending years of litigation involving the summit of Mauna Kea.

Although the snow-capped volcano is revered in Native Hawaiian culture, the area is also considered one of the best places in the world for astronomical observatories and hosts numerous facilities, despite the summit’s status as a conservation district.

The question before the court was whether the Hawaii Board of Land and Natural Resources had properly granted a permit to use the conservation district for construction and operation of the largest observatory, the Thirty Meter Telescope.

The telescope is being developed by an international consortium including the California Institute of Technology, the University of California, the National Institutes of Natural Sciences of Japan, the National Astronomical Observatories of the Chinese Academy of Sciences, the Department of Science and Technology of India and Canada’s National Research Council.

“Upon careful consideration of the written submissions, the applicable law, and the oral arguments, and for the reasons explained below, we now affirm the BLNR’s decision authorizing issuance of a Conservation District Use Permit (“CDUP”) for the Thirty Meter Telescope (“TMT”),” the majority ruled in its 73-page opinion.

The decision by Hawaii’s highest court means there are few paths left in the courts for those protesting the construction of the telescope. The plaintiffs could file a motion asking the court to reconsider its decision, said Hawaii Attorney Genera Russell Suzuki. And, he said, the plaintiffs could appeal to the U.S. Supreme Court, although he did not specify the grounds on which the plaintiffs could appeal.

The next step will be to submit plans to the Department of Land and Natural Resources for review and approval, a process that could take two years, DLNR director Suzanne Case said at a news conference following the decision.

Kealoha Pisciotta, the lead plaintiff in the case, said she was disappointed with the outcome, but added, “We really can say we did our very best to make our will known and to protect what we love.”

She declined to comment on whether protest demonstrations on Mauna Kea would continue.

“When you go into a court of law, how much more protest can you have?” she said.

KAHEA, a Native Hawaiian and environmental organization that helped represent the plaintiffs, also issued a statement, questioning one of the court’s conclusions.

“The opinion wrongly relies on representations that there is ‘no evidence’ of Hawaiian cultural practices on the specific acreage proposed for the TMT,” KAHEA said. “Thousands of Hawaiian cultural practitioners have affirmed the sacredness of the entirety of Mauna Kea. Thousands more have supported the protection of Mauna Kea from the TMT project. The Court’s opinion has done nothing to change this.”

KAHEA called on Gov. David Ige and telescope officials to move the project from Mauna Kea, despite the court’s opinion. But Ige gave no indication that the state would move the observatory site.

“We’ll have to see what happens with the project,” he said, when asked directly about KAHEA’s request.

Supporters of the telescope, meanwhile, said they were grateful to the court.

“We thank all of the community members who contributed their thoughtful views during this entire process,” Henry Yang, chair of the TMT International Observatory Board of Governors, said in a statement.

“We remain committed to being good stewards on the mountain and inclusive of the Hawaiian community. We will honor the culture of the islands and its people and do our part to contribute to its future through our ongoing support of education and Hawaii Islands’ young people.”

Read the Supreme Court’s opinion below: