The court ruled the State Lands Commission rule prohibiting development on public tidelands is not valid.
The justices called it an "underground regulation."
They said the rule has not gone through a California legal procedure which requires public comment before a regulation takes effect.
“The Land Commission's regulation covers land on the water side of the coastline,” said Attorney Marco Gonzalez, with Encinitas-based Coastal Environmental Rights Foundation.
He said the state holds as public property "all land seaward of the most landward historical position of the mean high tide line."
But Gonzalez said that's hard to pin down as erosion and sea-level rise changes the shoreline, shifting the mean-high-tide line landward.
"The appellate decision really gets at something that the State Lands Commission was using as a convenience regulation," said Gonzalez. “It is incredibly difficult to establish where the mean high tide is on the coast of California."
Gonzalez said he does not expect the decision to affect regulation of development along the coast.
But he said sea-level rise may continue to shift the tide lines landward, bringing more erosion.
"There's now a lot of work being done at the state level to address what we're going to do as the ocean creeps farther inland,” Gonzalez said. “And as we know even from this case, the mean high tide line moves inland with erosion and sea level rise. So, it puts things in flux, but it kind of lines them up as well to get some new legislation to more firmly establish how we're going to derive those numbers."
The case involved a couple in Carpinteria who wanted a permit to build a home on sandy beach parcel.
The State Lands Commission ruled the home would encroach on tidelands.
Gonzalez said he expects the Lands Commission will appeal the decision.
"If that happens, you can expect several environmental groups to support the appeal effort," said Gonzalez.
He said with sea-level rise and continued erosion, building right along the coast is a bad idea.
"Anybody building on the California coast needs to realize they're playing a game of roulette," said Gonzalez. "It may not be the best investment as it once was perceived to be to own the house right on the edge of the shoreline."
