Shanghai police patrol unlicensed vendors. According to the Law of People's Republic of China (PRC) on Public Security Administration Punishment, one of the duties of Shanghai police patrol is to maintain public safety and public order, including controlling unlicensed vendors, engaging in business activities without permission, occupying roads, venues and public facilities, etc. These are all illegal acts. The police have the right to stop and ban the business activities of unlicensed vendors and protect the rights and interests of citizens and public order.