When a patent application is written by an attorney, it is carefully crafted to claim something novel and inventive which still provides broad protection. So, after going to all that trouble, why would anyone then want to change the application later?


Patent applications are generally amended to overcome an objection raised by the Patent Office Examiner.  The objection may be that the claimed invention is not novel, perhaps due to some prior art which was not known about at the time of filing, but which surfaced during the official search.  The Examiner may also argue that the claimed invention is not sufficiently inventive because prior art is found which, whilst not actually anticipating the invention, point the skilled person towards it.


Where a valid novelty or inventive step objection is raised, it can usually be overcome by amending the claim.  The amendment will alter the claim to exclude those things which are not new, or not inventive, in the light of the newly-available prior art.



The most straightforward amendment is simply to combine one of the dependent claims in the application into the main claim.  The Patent Office Examiner will usually already have indicated whether or not each individual claim is objected to so, in principle, it should be possible to say at a glance whether such an amendment will overcome the objection.  That said, examiners are permitted to change their mind.


One of the advantages of including plenty of dependent claims at the time of application is that it can reduce the cost of prosecution, by providing the opportunity to make these very simple amendments to overcome any objections.




Whilst simply combining two claims is quick and cost-effective, sometimes it is not the best way to obtain the greatest possible level of protection.  After all, the prior art which is causing a problem was probably not known to the attorney who drafted the application, and so none of the dependent claims may be suitable for overcoming the prior art whilst retaining a reasonably broad claim.


It is possible to lift description from other parts of the specification into the claim.  This can be particularly useful when the prior art is really very different from the invention, but technically reads on to the wording of the claim.  By clarifying what the claim actually means, which should be possible if plenty of supporting description has been provided, it should be possible to come up with something which is novel over the prior art, without significantly giving up ground.


It can be possible to add things to the claims which are not specifically described, but which are clearly shown in the drawings.  However, it is far preferable to closely follow wording present in the application as filed, where possible.




Adding technical subject matter to an application after filing is strictly prohibited.  Any amendment which adds matter will lead to further objections from the Patent Office.


Matter is said to be added when the amended patent application teaches the skilled person something which he would not have learned by reading the specification as filed.  The rule is strict, and even a minute detail cannot be introduced into the specification if there was no basis for it on filing.


Perhaps counter-intuitively, subject matter can sometimes be added to an application by deleting words, if the resulting disclosure covers a broader range of things than were originally described.  For example, if the application as filed describes “a wheel with six spokes”, then deleting the word “six” will result in a description of a far broader range of wheels.  This is not allowed.


There is no outright ban on broadening the scope of a claim before a patent is granted.  However, broadening amendments can be difficult.  Where a patent application as filed points to a particular feature as being essential to the invention and gives that feature a great deal of inventive significance, then a skilled person is arguably taught something new when he is told that the particular feature does not have to be included after all.




Amendment after grant is also possible, and can be used to preserve the validity of a patent where further prior art comes to light.  Post-grant amendment is however subject to the additional restriction that the scope of protection cannot be extended.  In other words, the claim cannot be broadened at all.


It is absolutely vital that narrowing amendments which add matter are not made during the application process.  Even if the Examiner is prepared to allow such a claim, the resulting patent will be irretrievably invalid, because the added matter can only be removed by broadening the claim, which is impermissible.




Amendment is a normal part of the patent application procedure, and the vast majority of applications will be amended in some way before grant.  Post-grant amendment is less common, but does provide the flexibility to retain a valid patent when relevant prior art comes to light later.


No amendment can add technical subject matter, and so it is vital that full disclosure, including of optional features and combinations of alternatives, is provided at the time of filing.  This is one reason why patent applications should be drafted by a qualified patent attorney, who will need full details of the invention to do a thorough job.


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