New Zealand’s Patents Act 2013 took effect from 13 September 2014. Among the many changes brought about by the new legislation was the way in which the prior art base was defined. In combination with the fact that a New Zealand patent claim is afforded a single priority date only, this potentially gives rise to a perfect storm of self-colliding (or “poisonous”) divisional applications. At present, it is uncertain whether this scenario has come about by accident or design. However, a few pointers are now beginning to emerge.


New Zealand’s Patents Act 2013 (the “new Act”) has been in force now for a little over two years. Given that it takes on average (allowing for an appropriate degree of generalisation) about two years for a New Zealand patent application filed under the new Act to move from filing to acceptance, it is conceivable that many of the earliest-filed new Act cases will very soon be approaching their respective acceptance deadlines.

In respect of New Zealand practice, which requires that a divisional application is filed before its immediate parent is accepted, patentees have – or will soon have a decision to make: should we file a divisional? There are several reasons why filing a divisional application makes good strategic sense: unity, flexibility, a defensive position and a desire to seek greater/different claim scope being just some of them.

Divisionals under the Patents Act 1953

Previously, under the Patents Act 1953 (the “old Act”), New Zealand divisional practice was somewhat patentee-friendly. The requirement to file a divisional before the parent was accepted still existed. However, there was no restriction on the facility to “daisy chain” as many successive divisionals as the patentee desired. This has, of course, changed under the new Act such that a five-year limit has been imposed (i.e., no divisionals in a series can be filed after five years has elapsed from the filing date of the earliest ancestor application).

Introducing the self-colliding “poisonous” divisional

The fact that a New Zealand claim can have only the one priority date gives rise to some potential problems – especially when combined with the way in which the “prior art base” is defined under the new Act. Perhaps the most significant of these is known as the “self-colliding” or “poisonous” divisional. This concept has gained a fair amount of notoriety recently by way of the UK Patents Court decision in Nestec S.A. & Ors v Dualit Ltd & Ors [2013] EWHC 923 (Pat) (22 April 2013). The general concept at play is that where a claim in a divisional application is not entitled to the earliest priority date of its parent, it can then be anticipated by its parent.

The reverse situation is also true – a divisional application can anticipate its parent in cases where claims of a relatively broad parent application are not entitled the earliest priority date, but the relatively narrow claims of a later-filed divisional are.

It should be appreciated that the New Zealand situation does not directly mirror that of the UK because, under New Zealand law, provisional patent applications are not taken to form part of the prior art base. Conceptually, however, the notion of self-collision based upon the recent UK case law appears alive and well under the provisions of New Zealand’s new Act.

Under the old Act, members of the same patent family (e.g., a parent application and one or more divisional applications) needed only comply with the “prior claiming” provision and, in particular, section 14 of the old Act. This provision was somewhat narrow and intended primarily to prevent double patenting. By comparison, under the new Act, there has been adopted a “whole of contents” test for novelty. It is this definition that enables the threat of self-collision between a divisional application and its parent, and vice versa.

The potential for self-collision is heightened by the new Act requiring that the description within the patent specification adequately “supports” the claims. This is a higher standard than the “fair basis” requirement specified under the old Act. As such, any claim governed by the new Act will be more susceptible to forfeiting one or more of its priority claims (remembering that only a single priority date is allowed), which in turn, opens to door to the threat of a self colliding, poisonous relationship with its parent application.

Legislative accident or legislative intent?

It can be argued that the potential for self-collision is not simply an artefact of the way the new Act is drafted and that it is actually consistent with the intent of the new legislation. The draft legislation, dating back to late 2004, previously contained an “anti self-collision” clause attached to the definition of the prior art base, in order to prevent a divisional application anticipating its parent, or vice versa. However, this clause was then removed by the New Zealand Government during the final stages in the passage of the new Act.

On the one hand, the removal of the anti self-collision provision from the new legislation seems consistent with the overall tenet of the new Act. For example, throughout the new Act, the onus is increasingly being placed upon the patentee to “plant their flag” as quickly and definitively as possible. This onus should provide, relative to old Act applications, an increased degree of certainty to third parties from a very early stage in the patent process. As such, one could speculate that it was the intention of the legislature to provide a re-balance between the interests of patentees and third party interests.

On the other hand, the anti self-collision clause may have been removed to gain greater conformity with international norms. For instance, the corresponding clause had not been well received during negotiations toward the WIPO draft Substantive Patent Law Treaty (SPTL), which ran concurrently with the early stages of patent law reform in New Zealand. Indeed, Australia – New Zealand’s closest trading partner, lacks any such provision in its Patents Act 1990. On the other hand, it should be noted that patent claims in Australia are allowed more than one priority date; an anti self-collision clause would likely be redundant on this basis.

Thus, whilst the removal of an anti self-collision provision from the new Act may have been intentional, the potential consequences of such removal may not have been. To this end, we note the publicly-accessible dialogue between the New Zealand Law Society and the Ministry of Business, Innovation, and Employment (the Government Department responsible for administering the new Act) toward a possible amendment to the new Act to clarify the situation.

How could the Government correct poisonous priority (assuming it wanted to)?

If the New Zealand Government was to decide that poisonous priority should be removed, then the “fix” is actually fairly quick and easy. Indeed, New Zealand need look no further than many of its closest trading partners. For example, the United States and Japan have anti self-collision provisions in their respective patent laws; and Australia and Europe allow a claim to have multiple priority dates. Both solutions are available to the New Zealand Government should it perceive that poisonous priority is indeed an issue.

Prediction: Poisonous priority is here to stay

At present, the New Zealand Government is in the midst of what would be its quickest and easiest avenue to correct the poisonous priority situation, should it wish to. Specifically, the Patents (Trans-Tasman Patent Attorneys and Other Matters) Amendment Bill is presently awaiting its second parliamentary reading (we have reported on this legislation previously, within the guise of the Trans-Tasman “Single Economic Market” reforms and their likely abandonment).

As suggested in the section heading above, we do not see New Zealand’s position with respect to poisonous priority changing any time soon; if the Government wanted it removed, there would be, by this stage of the legislative process, clear indications that this was on the cards. There aren’t.

Specifically, the issue of poisonous priority was raised in a number of submissions made to the Commerce Select Committee during the earlier public consultation phase of the Amendment Bill. However, when the Committee released its recommendations on 13 July 2016, poisonous priority did not so much as rate a mention. Accordingly, it is difficult to envisage how a “fix” to this perceived issue could now be installed within the draft legislation before such time as it is passed.

Another reason why we feel that poisonous priority is here to stay was that when the anti self-collision clause was removed from the new Act by the very same Commerce Select Committee, this was done on that back of a single public submission having no reasoned analysis behind it. It is therefore possible that there were other forces at play here – and the above-mentioned third party dimension (which is a stand-out feature of the new Act) is very possibly the reason.

Has anyone fallen foul of the poisonous priority trap yet?

To the best of our knowledge, the answer is a clear “no”. This is likely the combination of a number of factors: Only a small number of new Act applications have been filed to date; of these, only a very small number of divisionals have been filed; and of these divisionals, it is reasonable to presume that a negligibly small proportion will ever have “issues” in respect of poisonous priority. In short, the sample size – both in terms of number and time, is too small for this effect to have yet raised its head in practice.

Falling foul of New Zealand’s poisonous priority trap is admittedly something of a long-shot. However, mitigating risk is what this industry is all about – and presumably nobody wants to be associated with the first New Zealand divisional to collide with its parent. To this end, it is all about being aware of the risks and mapping an appropriate strategy around them.


In conclusion, New Zealand’s new patent legislation requires patentees to very quickly establish and assert their patent position; there is a comparative lack of flexibility here which could be considered unduly restrictive.

What is clear, however, is that the new Act no longer allows patentees to use the divisional facility as a last minute bail out option. It does provide a divisional facility (out to the five year limit as discussed above) – but the threat of poisonous priority requires that from a strategic perspective, any consideration of whether to file, or not to file a new Act divisional application is best performed in conjunction with a New Zealand patent attorney who will be apprised of the risk/reward balance in venturing down this particular path.