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Plausibility Arrives in New Zealand: The High Court’s Adoption in Pharmalink v Pharmazen
The High Court’s judgment in Pharmalink International Ltd v Pharmazen Ltd [2025] NZHC 2657 represents the first time a New Zealand court has expressly adopted and applied the plausibility standard for sufficiency and support under the Patents Act 2013.
In an appeal from an opposition to grant of a patent at the Commissioner level, the Court ultimately upheld the refusal to grant a patent because the invention was not plausible across the breadth of the claims. This decision signals clear alignment with UK authority and sets a new, explicit benchmark for future pharmaceutical and biochemical patents.
The Court’s Adoption of Plausibility
Justice Downs recognised plausibility as a test for sufficiency and support. Drawing on UK jurisprudence in Regeneron v Kymab [2020] UKSC 27and Warner-Lambert Co LLC v Generics (UK) Ltd [2018] UKSC 56, the Court held that:
“an applicant must identify a plausible reason for believing the invention works across the matters claimed by the patent”.
This is the first judicial articulation of the plausibility standard in New Zealand. The Court emphasised that:
- the standard is “modest” and proof is not required,
- but speculation is insufficient, and
- plausibility must extend across the full scope of the claims.
Why the Claims Failed the Plausibility Test
The specification included laboratory data (Examples 2 and 3) showing synergy between PCSO‑524® (green‑lipped mussel lipid extract) and enriched krill oil. The Court accepted that synergy was plausible for the specific mixtures tested.
However, the claims extended far beyond the experimental evidence, covering:
- all green‑lipped mussel lipid extracts,
- krill oils with phospholipid content down to 40%,
- almost the entire spectrum of possible ratios, and
- multiple krill species.
Justice Downs concluded that the specification did not make it plausible that synergy would arise across this breadth, in doing so referring to a three step “chain of assumption:
- Lab results would replicate in the human body – accepted as plausible.
- Untested ingredients and ratios would behave like the tested ones – not plausible.
- Untested ingredients and ratios would behave similarly in vivo – also not plausible.
Some key takeaways
A. Plausibility is now a binding judicial standard in New Zealand
This decision brings NZ into line with the UK and will shape examination and litigation going forward.
B. Claim breadth must match the plausible technical contribution
Broad biochemical or therapeutic claims require either:
- extensive experimental coverage, or
- a mechanistic rationale that makes extrapolation plausible.
C. Unknown mechanisms increase risk
Where the mechanism of action is not understood, courts will be reluctant to accept broad claims.
D. Synergy claims require particular care
Because synergy is often narrow and ratio‑dependent, broad synergy claims without mechanistic explanation are vulnerable.
E. The patent bargain is central
The Court repeatedly emphasised that the monopoly cannot exceed the inventor’s demonstrated contribution.
A missed opportunity
Pharmalink represents one of the first opportunities for the High Court to consider support and sufficiency under the Patents Act 2013. With this is mind it was perhaps a missed opportunity to clarify more generally how the law has changed from the Patents Act 1953. Nevertheless it does seem that New Zealand courts are likely to take their lead from the UK Courts in this area.
Conclusion
Pharmalink v Pharmazen represents the first New Zealand judicial adoption of the plausibility standard. It signals a more rigorous approach to sufficiency and support, particularly for biochemical and therapeutic inventions.
While the Court did not take the opportunity to discuss the requirements for support and sufficiency more generally, it seems likely that UK law will continue to serve as a guide as to the direction New Zealand law will take.
David Nowak - April 2026
