Summary Offences Act 1981, s 23
It’s a criminal offence to obstruct a police officer or encourage another person to obstruct or resist a police officer. For this you can be jailed for up to three months, or fined up to $2,000.
This isn’t limited to physically interfering with an arrest – it can include giving false information, warning a friend who has committed an offence that the police are coming, or refusing to follow a lawful instruction.
Forming a human chain can be used to make it more difficult for individuals to be arrested. However, be aware that in some cases this could amount to the offence of obstructing the police.