The City of Los Angeles (defendant) enacted a zoning ordinance prohibiting the establishment of two or more adult book or video stores in the same building. The City cited a 1977 study that demonstrated a correlation between the placement of adult book and video stores and a higher incidence of violent crime and prostitution. Alameda Books, Inc. (plaintiff) sued the City, alleging that the zoning ordinance violated the First Amendment. The trial court granted Alameda Books’s motion for summary judgment. The appellate court affirmed, finding that the 1977 study did not adequately prove that the establishment of two adult book or video stores in the same building would lead to increased crime in areas in which they are located, and thus that the City could not reasonably rely on the study to demonstrate that the regulation served the City's substantial interest in reducing crime. The City petitioned for certiorari to the United States Supreme Court.