You may be familiar with the Pruneyard ruling from 1980 (Robins v. Pruneyard Shopping Center (1979) 23 Cal.3d 899, affirmed sub nomine Pruneyard Shopping Center v. Robins (1980) 447 U.S. 74). Under this case, California law permits the exercise of speech and petitioning in private shopping centers, subject to reasonable time, place, and manner rules adopted by the property owner. Essentially, the Pruneyard Court found that the shopping mall had become a public forum, replacing the streets and sidewalks of the central business district which, had been used for purposes of assembly and protest.
The Pruneyard case involved students soliciting support for their opposition to a United Nations resolution against Zionism. The Fashion Mall case involved a group urging shoppers to boycott one of the stores in the mall. The Fashion Mall owner had crafted a series of regulations and permitting for protests. However, they did not allow for boycotts: "Prohibits . . . 5.6.2. Urging, or encouraging in any manner, customers not to purchase the merchandise or services offered by any one or more of the stores or merchants in the shopping center."
Obviously this restriction on speech in the Fashion Mall's regulations is not content-neutral and therefore subject to a higher level of scrutiny. "The Mall’s rule prohibiting speech that advocates a boycott cannot withstand strict scrutiny. The Mall’s purpose to maximize the profits of its merchants is not compelling compared to the Union’s right to free expression." The Court concludes:
"A shopping mall is a public forum in which persons may reasonably exercise their right to free speech guaranteed by article I, section 2 of the California Constitution. Shopping malls may enact and enforce reasonable regulations of the time, place and manner of such free expression to assure that these activities do not interfere with the normal business operations of the mall, but 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."
This ruling is limited to California, as the California Supreme Court pointed out that the California state Constitution provides broader rights than the United States Constitution. But many other states also consider their state constitution to provide broader free speech rights than the United States Constitution, so the effect of this ruling may be felt by shopping malls across the country.
UPDATED: added updated link to case.