[ZenGum]

I've been thinking about threading this for a while, but haven't got the time to do the research to introduce it properly. Here is my half-assed attempt:

South Australia has had these laws for a few months now.
They are currently under court challenge.

The idea is that police can apply to have a certain group of people banned from associating with each other. The motorbike link is optional. The police provide the court with a list and appropriate evidence, and a judge can issue (or not) an order banning those people from seeing each other.
Appropriate evidence could be that they commit crimes with other members of the group in a regular and serious way, such as organising significant drug deals or violent crimes. See below for my One Reservation.

There is a precedent for limiting people's social interactions. A common (I think standard) parole condition is that you're not allowed to contact other parolees or ex-cons.

Australia does have some issues with bikie gangs. According to the media, and social gossip, they are deeply involved in interstate drug trades, and there have been many incidents of serious violence, including bombings and several multi-person shoot-outs. The Adelaide hydroponic industry is an example - liberal cannabis laws allowed up to 10 plants per person as non-criminal "personal use". Bikie gangs bought houses and converted them to grow-sheds, and mostly ran the drugs interstate. Home invasions and similar turf wars followed. Conspiracist rumour holds that the state government turned a blind eye because the state was in a bad financial and economic condition, and the cash was useful, but now there has been a mining boom and the govt has been cracking down (the truth of that last bit not guaranteed).

About three weeks ago four or five bikie gangs had a political ride just north of Adelaide to protest the new laws. Speeches were made, a political party was formed, a little good PR was generated.

A week later members of the Hells Angels and Comancheros happened to be on the same flight into Sydney, and although they managed to behave on the plane, a fifteen man brawl erupted in the arrivals lounge of the airport and one man was bashed to death. This was bad P.R. A week later the dead man's brother was gunned down outside his house.

In the last few months there have been several killings and a bombing or two. New South Wales (where Sydney is) adopted laws very similar to South Australia's.

In general I think the laws are a good idea, provided that it is done on a case-by-case basis and the people concerned get their chance to argue their case in court, but here is my One Reservation: the standard of evidence required in this case is lower than usual: "police intelligence" will be admitted. This could be information from an informer who is kept anonymous for their safety. While I see the point of that, this opens the door to these laws being abused against political opponents.