Policemen may use emergency powers in urgent situations.1 The powers available to the police under this section were also applied in Operation Saeta from 17-19 December 2005, immediately after the Cronulla riots, during which 16 vehicles and 56 mobile phones were seized2.
You were leaving an area where there had been a disturbance and the area had been placed under a lockdown. The law makes it clear that the police must not refuse permission to a person wishing to leave an area that has been cordoned off "unless it is reasonably necessary to do so to avoid a risk to public safety or to the person's own safety."3 But the expanded powers under Section 6A as mentioned above, do allow the police to prevent people entering and even leaving, authorized target areas where there is or has been large scale disorder. These provisions under Section 6A were also applied on 19 March 2006, to set up roadblocks and prevent cars exiting Brighton Le Sands from moving towards Cronulla, to prevent what police perceived to be threatened public disorder event. Thus, I believe Constable Green's confiscation of your phone and car may have been within legal limits.
In reference to your arrest, a person may be arrested for a breach of the peace when the policeman making the arrest has a reasonable apprehension of imminent danger of a breach of peace.4 However, if an arrest is to be lawful, an arresting officer must inform the arrestee of the grounds for arrest, at the time of arrest or as soon as practicable, failing which there can be grounds for a possible claim for damages5 because the police can only do what is practicable.6
The recent case of Coleman v Australia7 raised the issue of interference with individual rights through the application of the provisions of the Law Enforcement (Powers and Responsibilities) Act 1997. The complained was arrested and detained for five days and contested the case under his right to freedom from arbitrary detention under Article 9 of the ICCPR. The Court in this case, found that there had been a violation of the complainant's human rights.
Despite the existence of the new expanded powers available to the police as I have cited earlier, they are also required to arrest a person only as a last resort.8 There is a requirement to give information and warnings when the police are exercising their powers.9 On this basis, you may be able to contest the decision by the police officer to make an arrest, since such an arrest would not be justified in an instance where only a limited power of arrest applies.10
If I can be of further assistance, please let me know.