As most patent applicants know, the patentability of an invention is determined by comparing the invention to the pool of public knowledge that existed before the date the application was filed. If the comparison shows that the invention was already known to the public then the application will die.
There are so many patents, journals, newspapers, internet websites, and social media outlets making up this vast knowledge pool that surviving this comparison with the plethora of public knowledge is hard enough.
But did you know that one’s own patent applications can self-collide and destroy each other?
This unusual phenomenon of self-collision is termed “poisonous priority” or “toxic priority” and has been the subject of judicial attention recently in Europe,[1] Australia,[2] and New Zealand[3].
Poisonous priority can occur within a particular family of applications that, in the eyes of an applicant, relate to the same invention but are actually of slightly different scope. The self-collision typically occurs in scenarios (i) and (ii) below.
(i) A first filing (priority application) and a second filing (PCT application) claiming priority to the first filing.
(ii) A parent application (e.g. PCT) and a child application (e.g. divisional) that is filed later from the parent application. In examples (i) and (ii), the broader “fruit” invention including apples, bananas, grapes etc. was disclosed for the first time on the day the PCT application was filed. In contrast, the “apple” retains the benefit of the earlier filing date of the priority application. This entitlement to an earlier filing date and eventual publication of the narrower “apple” results in poisoning of the broader “fruit”.
With respect to (ii), it is standard practice to file a divisional application with the original description of the parent application. Thus the apple is published with the divisional application even though protection for the apple is not sought in the divisional application.
So how do you avoid being poisoned by your own application?
(a) Avoid replacing narrow terms with broader terms in later filed applications. For example, do not replace apple with fruit, gold with metal, and C1-5 alcohol with C1-10 alcohol. Instead, try to quarantine existing subject matter (apple, gold, C1-5 alcohol) from new subject matter (fruit excluding apples, metal excluding gold, C6-10 alcohol) in the later application. A good practice is to preserve the text of the earlier application and simply add in the new subject matter.
(b) Always explicitly recite alternatives of the broader concept. For example, if the first filing recites apple then the second filing would recite apple, banana, grapes, or rockmelon. A separate embodiment can be directed to the broader “fruit”. This is another form of quarantine and provides multiple fall back positions if the priority date of certain subject matter is questioned.
(c) Make your first filing an Australian or US provisional application as this type of application is never formally published by the respective Patent Office. Although such provisional applications become publically available in an associated PCT online record later, they should not count as a formal publication. Unfortunately, it is not possible to stop publication of a divisional application and carving out unnecessary subject matter (the apple) from a divisional application is not always feasible.
(d) Consider withdrawing any first filing (e.g. priority application) before it publishes. This is most important in Europe where there is no equivalent to an Australian or US provisional application.
With a little care patent applicants can focus on worrying what their competitors are contributing to that extensive array of public knowledge.
[1] Enlarged Board of Appeal Decision G1/15 (1 February 2017).
[2] AstraZeneca AB v Apotex Pty Ltd [2014] FCAFC 99.
[3] Patents Act 2013 (commenced 13 September 2014).