the CJA is the Criminal Justice and Public Order Act 1994 – section 63 of it gives greater power to the Police to close down unlicensed raves with force. This can happen for any gathering over 20 people if one person in the vicinity disagrees with the rave, claims they are “alarmed or distressed” by the event and contacts the Police.
This means the Police can use a PSU “public safety” unit which is the new politically correct term for the “riot squad” if the ravers do not move on quickly.
Cops here have access to batons, shiellds and irritant spray, but it is unusual for armed police to close down raves in this country although its recently happened in London (because a gang had targeted the event) and armed units are increasingly on standby on the sidelines.
it is similar to the RAVE act but I think your act is aimed more at combating licensed events due to drugs. We do also have laws like that as well, which is why in the UK unlicensed parties were or are commonplace in some areas – often to get away from the anti-drugs security measures.