SAN FRANCISCO — Shopping malls can't stop protesters from calling for boycotts of their stores, even when they're on mall property, the California Supreme Court has ruled.

In a 4-3 decision, the justices ruled that California's free-speech protections extend to demonstrators who set up inside shopping centers and urge customers not to shop there.

The Dec. 24 ruling in Fashion Valley Mall, LLC v. National Labor Relations Board upholds a 1979 state Supreme Court decision — Robins v. Pruneyard Shopping Center — that found shopping malls are public forums in which people's free-speech rights are protected by the California Constitution.

The case ruled on this week stems from a 1998 incident at the Fashion Valley Mall in San Diego in which members of a labor union from the San Diego Union-Tribune newspaper were forced out for distributing leaflets urging the boycott of the Robinsons-May store, one of the mall's tenants.

The union was involved in a labor dispute with the Union-Tribune and wanted to hurt Robinsons-May's business because the retailer advertised in the newspaper. The mall kicked the protesters out based on its rule that demonstrators on mall property can't demand a boycott of mall stores because it would hurt business.

The court ruled on Dec. 24 that malls can enforce regulations on demonstrations to assure they don't interfere with normal business, but they can't block speech based on its content, such as calling for a store boycott.

"A shopping mall is a public forum in which persons may reasonably exercise their right to free speech" guaranteed by the California Constitution, Associate Justice Carlos Moreno wrote for the majority.

Associate Justice Ming Chin, writing for the dissenting minority, said the court was giving too much leeway to demonstrators.

"The only tradition that is relevant to this case is the tradition, followed in most of the country, of finding no free speech rights on private property," Chin wrote. "The majority is trampling on tradition, not following it."