SAN FRANCISCO — A Silicon Valley billionaire’s extraordinary claim to own the tidelands and submerged lands off his property on the San Mateo County coast appears to have died.

An attorney for venture capitalist Vinod Khosla conceded the point Wednesday during oral arguments before a panel of state appellate judges in one of two lawsuits that seek to restore public access to Martins Beach, a secluded cove south of Half Moon Bay.

The lawsuit, brought by a handful of surfers calling themselves Friends of Martins Beach, makes two arguments for reopening the beach, which for many decades was available to the public in exchange for a parking fee. The three-judge panel for the 1st District Court of Appeal in San Francisco seemed skeptical of one and supportive of the other.

As for the notion that Khosla owns acres of land beneath the Pacific Ocean, Friends of Martins Beach attorney Gary Redenbacher said he expects it will simply go away.

“My belief, listening to the justices,” Redenbacher said, “is that it’s totally dead and should have been dead from the beginning.”

The claim is rooted in San Mateo County Superior Court Judge Gerald Buchwald’s April 2014 decision in the Friends of Martins Beach case. In ruling that Khosla did not have to allow visitors onto his property, Buchwald unexpectedly granted ownership of the offshore lands to the tech mogul.

That summer, Rusty Areias, Khosla’s lobbyist, trumpeted the assertion in Sacramento hearing rooms while fighting Martins Beach-related legislation.

“To get to the public beach you’re going to have to go 300 feet out into the ocean,” Areias told an Assembly committee on June 24, 2014.

The California Coastal Commission, which regulates coastal development, and the State Lands Commission, which holds tidelands and submerged lands in trust for the benefit of the public, filed an amicus brief urging the appeals court to reverse Buchwald’s finding.

In the document, the agencies called Buchwald’s decision a “grave error” that could severely compromise their ability to regulate coastal affairs up and down California.

Under questioning Wednesday by Justice Theresa Stewart, attorney Dori Yob said the court could simply strike the language from their pleadings.

“We all agree that nobody is asking for that land,” said Yob, who declined to comment after the hearing.

The fundamental question posed by Friends of Martins Beach is whether the California Constitution gives the state the authority to require a private property owner to let the public cross his land to reach the ocean.

Based on their questions Wednesday, the justices appeared ready to dismiss that argument, because Martins Beach passed into private hands, through a provisional Mexican land grant, before California became a state in 1850. The U.S. Supreme Court upheld the patent on the land in 1859, quieting title to the property.

But the justices were receptive to Redenbacher’s secondary argument that the previous owners of Martins Beach, the Deeney family, created a public easement on their property through what’s known as “express dedication.” In other words, by inviting the public for nearly a century to cross their land to reach the sea, the Deeneys made the offer permanent, according to Friends of Martins Beach.

Redenbacher said he expects that, if the panel overturns Buchwald’s ruling on express dedication, the matter will go to trial in Superior Court. He added he plans to appeal to the California Supreme Court if he loses his constitutional argument. A ruling is expected later this year.

The other Martins Beach lawsuit, brought by the Surfrider Foundation, tackles a different issue. Surfrider contends Khosla, who bought Martins Beach in 2008 for $32.5 million, violated the Coastal Act in 2010 by failing to obtain a coastal development permit before locking the gate on the road leading to the beach from Highway 1. That case is also under appeal.

Meanwhile, the three voting members of the State Lands Commission will soon consider whether to use eminent domain to purchase access to the beach along private Martins Beach Road.

Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.