@shye428 FYI.
When is a police certificate required?
If you are over the age of 16 and have lived in any of the countries listed on this page for a total of one year or more in the last 10 years, you must get a police certificate from that country.
The certificate must cover the period of time from the issue date back to the age you ceased to be a minor, or must cover the whole time you were in a country.
For immigration purposes a police certificate is deemed to be valid for 12 months from the issue date.
source: https://www.border.gov.au/Trav/Visa/Char