Under the ordinance, property owners, lessees, managers, party producers, promoters, sponsors, entertainers and DJs would be fined if a party venue does not have a city amusement license, the Chicago-Tribune said.

The law requires rave organizers to register their parties, which must end by 2 a.m., and these events must adhere to stringent fire safety codes and restrictions for building size and capacity. In the past, raves were held in lofts and vacant factories, and went largely unregulated.

For years, Windy City teens have paid $5-$25 to attend underground raves, which usually started after midnight and lasted till around 10 a.m., the Chicago Sun-Times said. Authorities are concerned about extensive use of drugs like Ecstasy and nitrous oxide at the events.

The ordinance’s DJ provision is vital because he is the least mobile, Shakespeare District Police Sgt. Tim Edeling told the paper. “The DJ really can’t leave because he has thousands of dollars worth of equipment tied up there. … A lot of these bigger events will fly their DJs in from around the country. … They’re the headliners who bring the kids out. If DJs know it’s dangerous to come to Chicago because you could face up to a $10,000 fine, they may think twice about coming here.”