12 May 2013

Raising the Bar – New Life for Patents of Addition?

AdditionIf you have never heard of a ‘patent of addition’, I am sure that you are not alone.  Even those of us who practice in a jurisdiction in which these beasts are rumoured to exist have rarely, if ever, actually seen one.  It is not even easy to track one down, or to find out how many of them there may be out there in the wild, since IP Australia’s AusPat database does not provide a facility to search specifically for applications and patents of addition.

However, readers experienced with US patent law and practice may already be familiar with the basic rationale behind the patent of addition, which has much in common with what is known as ‘non-statutory obviousness-type double patenting.’  The principle applied in both cases is that an applicant can be permitted to obtain a second patent for a new, but obvious, variation of an invention already claimed in an earlier patent, but that the second patent may not outlive the first.  In this way, the patentee’s rights are insured, but not improperly extended.

It is possible that one reason why patents of addition have been uncommon in Australia is because the law relating to inventive step has been so weak that they have generally been unnecessary (see my recent article on Australia’s ‘four laws of inventive step’).

However, with the commencement of the Raising the Bar reforms in Australia on 15 April 2013, perhaps the patent of addition will have a new lease on life.  After a decade in the Australian patent profession, I have yet to set eyes on an actual application for a patent of addition, but I have been involved with a number of US applications in which obviousness-type double patenting objections have been raised.

If there is anything to this theory, applicants and their advisors in Australia will want to make sure that they are sufficiently familiar with the patent of addition to identify when it might be useful.

Why Are Patents of Addition Needed?

The fundamental issue addressed by both the patent of addition and the US doctrine of obviousness-type double patenting is how to deal with a situation in which an applicant files separate applications for two inventions which are different, but not enough so to be independently patentable. 

One example of this is when a first application is filed for an invention ‘A’, followed sometime later by a second application for an invention ‘B’ which is an obvious variation or improvement of ‘A’.  It should be noted that ‘B’ need not be obvious over ‘A’ alone.  It may be that ‘B’ is obvious over ‘A’ in combination with some other item of prior art information, which the inventor may not have known about until the later application is examined.  This is, in fact, the situation in which I have encountered obviousness-type double patenting rejections in US cases.

If ‘B’ is obvious, i.e. lacks an inventive step, when compared with ‘A’, should the applicant be entitled to a second patent? 

If the application for ‘A’ is considered to be prior art, just like any other earlier disclosure of the invention, then the answer would be ‘no’.  But is this really fair on the applicant, who probably did the right thing by filing an application for the original invention ‘A’ at an early stage, before developing the improvement ‘B’?  And is it really in the public interest for the system to deny a patent for ‘B’?  This just provides an incentive for inventors to keep improvements secret, where possible, rather than applying for a patent which results in public disclosure, but may be denied on grounds of obviousness.

On the other hand, if inventors were permitted to carry on obtaining new patents for obvious variations of their own previous inventions, then they could keep extending patent rights without adding anything new to the stock of human knowledge.

The compromise solution to this dilemma, in the US and Australia, is to permit the applicant to have a second patent, but to limit its term so that it cannot continue to be in force after the original patent has expired.

Patents of Addition vs Terminal Disclaimers

In the US, the doctrine of obviousness-type double patenting is non-statutory, i.e. it was developed by the courts, rather than having been written into legislation by Congress.  There is, therefore, no special ‘type’ of patent which can be issued for a subsequent invention which is new, yet obvious, over an earlier invention by the same applicant.

Instead, if the applicant wants the second patent to issue, they must enter a ‘terminal disclaimer’, which is a fancy way of saying that they agree that the second patent will automatically expire at the same time as the first one.

A patent of addition achieves substantially the same thing, by a different mechanism.  This special type of patent, which is governed by section 80 to section 87 of the Patents Act 1990, is tied to the patent for the ‘main invention’ (just like a divisional application is tied to its parent), and can only exist for as long as the main patent remains in force: section 83(1).

Advantages of Patents of Addition

Patents of addition are arguably better that US follow-on patents with terminal disclaimers for two reasons.

Firstly, maintenance fees are not payable on a patent of addition: section 86.  So long as the main patent is maintained, the patent of addition remains in force also.

Secondly, patents of addition are immunised not only against obviousness over the main patent, but also over any public use of the main invention itself, e.g. through public commercial promotion or sale.  In particular, section 25 provides that:

Objection cannot be taken to a patent request or complete specification in respect of an application for a patent of addition, and a patent of addition is not invalid, merely because the invention, so far as claimed, does not involve an inventive step, having regard to the publication or use of the main invention….

While terminal disclaimers in the US can be used to overcome citation of a patent application for the main invention, they cannot save a patent from invalidity over some other prior publication or use of the main invention by the inventor more than one year prior to filing of the second application.

So What’s Changed to Make Patents of Addition More Useful?

A patent of addition is only of benefit to the applicant in order to avoid invalidity due to lack of inventive step over a publication or use of the main invention.

Under the 1952 Act, i.e. prior to 30 April 1991, obviousness was assessed only against the common general knowledge of the skilled person in the relevant art.  This meant that it made no difference that the main invention was subject of an earlier application.  Unless the main invention and the improvement or modification were established common general knowledge, the claims of the later application would be inventive.  In almost every case, then, there would be no need for a patent of addition.

Things were not much better under the original 1990 Act.  Only one item of prior art information (i.e. publication or use) could be added to the common general knowledge, and only then if it would have been ‘ascertained, understood and regarded as relevant’ by the skilled person.  So, unless either one or both of the main invention and the improvement or modification were established common general knowledge, there could be no prospect of the claims of the later application being found obvious.  Again, there was very little need for patents of addition.

Even when the ability to combine information from prior disclosures was introduced from 1 April 2002, there were still the hurdles of establishing that both prior art references (e.g. disclosing, respectively, the main invention and the modification) would have been ascertained, understood and regarded as relevant and that the skilled person would have combined the information in the required manner. 

Finally, however, with the Raising the Bar reforms, these onerous hurdles have been removed.  The law relating to inventive step should now be more closely aligned with the US approach, meaning that many cases in which an obviousness-type double patenting issue would arise in the US will create a similar objection of lack of inventive step in Australia.

When this occurs, it will be possible to overcome the objection by converting the ordinary standard patent application into a patent of addition, which is a simple matter of requesting amendment of the patent request, under section 104 of the Patents Act.


Of course, I am speculating here, and we will just have to wait and see whether patents of addition take on a more important role in the future.

However, my professional experience is that obviousness-type double patenting objections are not uncommon in the US, whereas patents of addition have been very uncommon in Australia.  It therefore seems to me that with the law of inventive step now more closely aligned between the two countries, there could well be a new life for patents of addition.


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