In early September New Yorkers may have noticed an unwelcome guest hovering around their parties. In the lead-up to Labour Day weekend the New York Police Department (NYPD) said that it would use drones to look into complaints about festivities, including back-yard gatherings. Snooping police drones are an increasingly common sight in America. According to a recent survey by researchers at the Northwestern Pritzker School of Law, about a…