California Online Privacy Protection Act

The California Online Privacy Protection Act of 2003 (CalOPPA), effective as of July 1, 2004 and amended in 2013, is the first state law in the United States requiring commercial websites on the World Wide Web and online services to include a privacy policy on their website. According to this California State Law, under the Business and Professions Code, Division 8 Special Business Regulations, Chapter 22 Internet Privacy Requirements, operators of commercial websites that collect Personally Identifiable Information (PII) from California's residents are required to conspicuously post and comply with a privacy policy that meets specific requirements.

Source: Wikipedia — California Online Privacy Protection Act (CC BY-SA 4.0)