The Law
Section 102 of the Australian Patents Act provides that new material can be added into an Australian patent application without loss of priority date. However the result must not be matter claimed that was "not in substance disclosed" in the specification as originally filed.
Amendments to the Descriptive Portion
Consequently, additional description can often be added to an Australian application to overcome objections that the specification is ambiguous or lacking in clarity.
Further embodiments or drawings, which fall within the framework of the original disclosure can also often be added to the specification. But care must be taken that the inclusion of that further material will not result in claiming matter that wasn't in substance disclosed in the specification as filed. Such amendments can be made to ensure that the specification complies with best mode requirements.
For example, consider a patent application originally filed with a claim for a boat trailer having a resilient suspension member. The detailed description refers only to a suspension member in the form of a leaf spring. In my experience an improved embodiment incorporating a coil spring could be added to the description. I understand that such an addition would not be permissible in the USA or before the EPO.
Amendments to the Claims
The claims can be broadened if the amendment does not result in matter being claimed that was not "in substance disclosed" in the specification as originally filed.
The "in substance disclosed" test does not necessarily require that the subject matter was explicitly disclosed at the time of filing. It suffices if the claimed subject matter is implied in the description as filed, when read by the expert skilled worker in the relevant technical field. (United-Carr Incorporated's Application (1971) RPC 23.)
According to the Australian Patent Examiner's Manual:
"Generally, if further embodiments or illustrations which fall
within the framework of the original disclosure are added to the
specification, the inclusion of that further material in a claim
will not result in claiming matter not in substance disclosed."
For example, consider a patent application with a claim for a boat
trailer having a coil spring suspension and a detailed description
referring only to a coil spring suspension. In my view the
Australian Patent Office would accept an amendment to broaden the
claim to a boat trailer having a resilient member suspension.
When can these amendments be made?
The above amendments to either the description or claims of the specification can be lodged up until the time of acceptance. The flowchart of Australian national phase procedure indicates when acceptance is expected.
Official fees are payable if an amendment is lodged before requesting examination. That fee can be avoided by lodging the amendments simultaneously with the examination request.
Limitations after Acceptance
After acceptance, an amendment of a claim is not allowable if the amended claims do not in substance fall within the scope of the claims prior to amendment
Thus, an amendment resulting in anything constituting an infringement prior to the amendment is not permitted.