SACRAMENTO, Calif. — A Sacramento appeals court says California’s union-backed 1975 law allowing labor picketing outside stores is unconstitutional because it requires property owners to host speakers they disagree with.

Courts have allowed picketing and political activity outside shopping malls, saying they are exercising freedom of speech.

The Third District Court of Appeal ruled yesterday in favor of a Ralphs Grocery-owned Foods Co market in Sacramento, which was in a dispute with the United Food and Commercial Workers union. The union picketed five feet outside the market.

The appeals court agreed with Ralphs that the law was invalid because it singled out union speech for special protection.