The Hawaii Supreme Court heard arguments Thursday in an appeal that could determine whether an embattled multi-nation telescope project can be built on a mountain Native Hawaiians consider sacred or have to move to a backup site in Spain's Canary Islands that's less desirable to scientists hoping to use the instrument for groundbreaking discoveries.

Much of the arguments centered around whether it was a conflict of interest for a hearings officer who made a key recommendation in favor of the project to be a member of a Hawaii astronomy center.

The state allowed retired judge Riki May Amano to preside over contested-case hearings for the contentious project despite complaints from telescope opponents who decried her paid membership to the Imiloa Astronomy Center.

The Big Island center is connected to the University of Hawaii, which is the permit applicant.

Opponents appealed to the Supreme Court after Amano recommended granting the permit and the state land board approved it.

"She should have never presided over the case," Richard Wurdeman, an attorney representing telescope opponents, told the justices. He noted the center included exhibits about the project planned for the Big Island's Mauna Kea, Hawaii's tallest mountain.

Amano was just a casual member of the center, a "remote and tenuous relationship" that doesn't create an appearance of impropriety, state Solicitor General Clyde Wadsworth told the justices.

Associate Justice Richard Pollack asked why Amano later cancelled her membership in response to the concerns. Wadsworth said the cancellation was not a concession of bias.

This is the second appeal before the high court involving the Thirty Meter Telescope. Justices are already considering another appeal challenging the state land board's decision to allow the University of Hawaii to sublease mountaintop land to telescope builders.