The California Supreme Court ruled Monday that shopping malls cannot stop protesters from urging a public boycott of the stores, even if the demonstrators are on mall property.

The 4–3 decision upholds a 27-year precedent protecting free speech rights at shopping centers, even if the malls are privately owned.

The case started in 1998, when the pressroom union was embroiled in a contract dispute with the San Diego Union-Tribune newspaper. Thirty to 40 union members stood in front of a Robinsons-May store, one of the Union-Tribune’s biggest advertisers, cataloging their grievances and urging customers to contact the chief executive of the newspaper. Officials at the Fashion Valley Mall in San Diego told the protesters to leave, saying that if they wanted to resume their demonstration, they would have to sign a pledge not to urge a boycott of any store because it would hurt business.

Justice Carlos Moreno, writing for the majority, agreed that the mall could regulate protests but said the state’s Constitution barred mall rules for protesters based on the content of their message. “They may not prohibit certain types of speech based upon its content, such as prohibiting speech that urges a boycott of one or more of the stores in the mall,” Justice Moreno said in the ruling. Chief Justice Ronald George and Justices Joyce Kennard and Kathryn Mickle Werdegar joined in the decision. In dissent, Justice Ming Chin said the court was treating private property as a “public free-speech zone.”