It is a offence in Victoria to "assault, resist or hinder" or to incite someone else to "assault, resist or hinder a member of the police force in the execution of his [ sic ] duty", including the making of an arrest (section 52(1) Summary Offences Act 1966 (Vic) ). "Resisting" means opposing by force and "hindering" means making the arrest or other police action more difficult to carry out. It does not matter whether the resistance or hindrance actually prevents the arrest or other action.
It is not an offence to passively resist arrest, or to run away before an arrest has commenced. An arrest commences when the police officer makes it plain to you by words or other action that you are under arrest.
It is not an offence to resist or hinder a police officer who is not acting in the execution of his or her duty. Police may not be acting in the execution of their duty when they make an illegal arrest, or use excessive force. It is a defence to the charge of resisting you did not know that the person who you resisted was a police officer. The maximum penalty is six months' jail or a fine of $2500. An assault police charge will attract a more serious penalty than resisting or hindering.
Some people convicted of assaulting police have been sentenced to imprisonment. However, every case is different, and you should seek legal advice about the penalty you may face in your specific circumstances.
There are also more serious charges of threatening injury to police to prevent arrest, and a more serious assault police charge under sections 30 and 31 of the Crimes Act 1958 (Vic), which carry maximum penalties of 5 years imprisonment.
It is a Commonwealth offence to "intentionally and knowingly obstruct, resist, hinder, use violence against, threaten or intimidate" a member of the Australian Federal Police carrying out a "function or duty" (section 149(1) Criminal Code Act 1995 (Cth)). The maximum penalty for this offence is two years' jail.
It is also an offence for someone to obstruct, assault, threaten or abuse an authorised officer in the performance of his or her functions under the National Parks Act 1975 (Vic) (s.45(i)).