There is a new trial JP Desk at Barangaroo, Sydney CBD -> currently operating each Tuesday and Friday between 11:30 a.m. to 2:00 p.m. The desk is located in Tower 3.
A Justice of the Peace (JP) is a person appointed by the Attorney-General to act as an independent and objective witness to documents people use for official or legal purposes.
There are Document Witnessing Centres located at many metropolitan and regional locations. This link shows centre addresses, phone numbers and opening days and times. It is recommended that you contact a centre before attending to ensure that a JP is available.
How to find a Justice of the Peace or Commissioner for Oaths in the Northern Territory? including applying to become a JP or Commissioner for Oaths.
By virtue of the Oath of Office taken at the time of their appointment, ACT Justices of the Peace undertake to 'well and truly serve in the office of justice of the peace of the Australian Capital Territory'.