The Legal Aid Society and privacy advocates have called for a ban on the use of drone surveillance by the police at protests, as reported by Newsday.

At six recent social justice protests held in Long Island, Nassau County Police Department drones appear to have been present, according to an analysis of the flight records, obtained through a Freedom of Information Law request. Civil liberties experts worry that fears of electronic surveillance may prevent protesters from exercising their 1st amendment rights.

“I think it has a chilling effect,” said Jerome Greco, Supervising Attorney of the Digital Forensics Unit at The Legal Aid Society, of the use of the law enforcement drones at protests. The idea of being surveilled or recorded “makes people less willing to go out and lawfully express their opinions.”