“New Zealand’s current regime is more closely allied with other countries, including Australia, than it was before.” – Sam Ting
By Julius Melnitzer | February 3, 2026
New Zealand and Australia both allow divisional applications. Although both prohibit double patenting, their laws and rules are not the same, and recent developments in New Zealand have narrowed the differences.
New Zealand
Before 2021, New Zealand had one of the strictest double patenting regimes in the common law world.
Examiners interpreted the standard found in the Patents Regulations, which prohibited divisional claims “for substantially the same matter”, as applying to any divisional claim wholly encompassed by the parent claim or substantially identical in scope.
“Generally speaking, substantial overlap was not permissible and application of the rule was somewhat vague,” says Sam Ting, a senior associate in the Wellington office of AJ Park Law Limited, a member of the IPH network.
All that changed with the 2021 decision of the New Zealand patent office in Oracle International Corporation. Subsequently, the Intellectual Property Office of New Zealand (IPONZ) amended its Examination Manual to correspond with Oracle.
“Oracle originated the ‘double infringement’ test in New Zealand, so that, going forward, double patenting was only established if the parent claim necessarily infringed a divisional claim and vice versa,” Ting says. “This meant that applicants could make two separate filings for the same invention as long as the claims didn’t overlap completely.”
The upshot is that partial overlap and wholly encompassed claims became permissible, so long as the “double infringement” test did not apply.
“One caveat is that examiners will disregard trivial or arbitrary differences in determining whether the overlap is substantial,” Ting says.
From a procedural standpoint, New Zealand’s absolute filing deadline for divisional patents complicates matters. Divisionals must be filed before the acceptance of the parent filing and no more than five years from the effective filing date—but of the parent, not the divisional. Jurisprudence has established that only “exceptional circumstances” warrant extensions.
For the most part, the current regime benefits applicants, but there are still some difficulties.
“The five-year absolute filing deadline combined with examination delays means applicants often need to consider their divisional filing strategy well before examination,” Ting says.
Despite the liberalisation, however, New Zealand’s regime is still not as forgiving as the one in Australia.
“But New Zealand’s current regime is more closely allied with other countries, including Australia, than it was before” Ting says.
This being said, the prosecution risk is still undoubtedly greater in New Zealand.
Australia
Australia’s Patents Act 1990 prohibits double patenting only if an application “claims an invention that is the same as an invention that is the subject of a patent by the same inventor”, and the relevant claims have the same priority date.
Indeed, the double patenting prohibition has been interpreted so narrowly that the Australian Patent Examiner’s Manual guidelines make it unlikely that a double patenting objection will be raised during prosecution. And because applicants can amend at any time, early objections are largely pointless.
The fact that there is no absolute time limit for filing divisionals in Australia represents another key difference from the New Zealand regime. So long as the parent is still pending in Australia, then, divisional filings are permitted.
The upshot is that double patenting rarely raises issues in Australia, and if they do, only post-grant.
Julius Melnitzer is a Toronto-based writer who focuses on law, legal affairs, and the business of law. Follow him on LegalWriter.net or email him at julius@legalwriter.net