Criminal Procedure Act 2011, ss 6, 71
These are offences where you can only be fined, or sentenced to a community-based sentence like community work or supervision, rather than jail. You’re case will be seen at the District Court, and usually by a Justice of the Peace or a Community Magistrate rather than a judge.
An example of a category 1 offence is careless driving (that doesn’t cause injury or death).