“Just because you buy the front house, doesn’t mean you own the beach,” says Tony Salaza. “The beach is for everybody.” He gestures towards a sweep of architect-designed houses to his left. Over the past few years, many of Malibu’s 13,000 residents have been watching with alarm as public access rights to the 27-mile coastline have come under threat. Many celebrities and multimillionaires own sprawling Malibu homes overlooking the Pacific, including actors Robert Redford and Angelina Jolie, the rapper Dr Dre, the director Rob Reiner and media mogul David Geffen. In an effort to protect their privacy, some homeowners have...