Identifying Grounds for Patent Invalidity: 8 Prior Art Pitfalls

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A patent invalidity search is a prior art search performed on a granted patent to invalidate the claims of the patent (also referred to as subject patent) on grounds of novelty, obviousness and/or inventive step. These searches are conducted in order to identify relevant patent as well as non-patent literature those are in line with the claims of the subject patent and are generally overlooked by the examiner during examination.   

Table of Contents

When is an invalidity search performed?

Invalidity searches are performed in following scenarios: 

When a patent owner (plaintiff) files an infringement suit against an alleged infringer (Defendant) in the court of law for unauthorized/ unlicensed/ illegal use of his patented invention, the defendant resorts to invalidity search to render the claims invalid. Once the patent grant is declared invalid, there will be no infringement suit.  

A validity search may be sought by a patent holder to check validity of the claims before suing an alleged infringer. If no satisfactory prior art is identified during the search, the claims of the subject patent are assumed to be novel, non-obvious and have an inventive step. This assures the patent holder that they can file a case against potential infringers.  

Validity search can be performed on behalf of a potential licensor interested in licensing an invention. The interested party (licensor) would need license from the patent holder to manufacture or sell the products disclosing by the claimed invention. Thus, before investing a huge amount and time in the process or licensing, the potential licensor requests a validity search. This helps the licensor to determine strength of portfolio of the patent/patents of inventor/assignee they are going to license.  

When a company1 is interested in acquiring a company2 in order to take hold of the IP portfolio owned by company2; company1 requests patent valuation and validity search on the patent portfolio to determine the strength of the patents of the company2. A patent that has valid claims adds more value to the patent.   

Identifying Grounds for Patent Invalidity

Following grounds must be identified during an invalidity search:  

  1. Presence of a published prior art or public use or sale of the patented technology, product, process, or service before the earliest priority date of the subject patent in question. This signifies that the invention was not novel at first place and was wrongly granted. 
  2. Insufficient or missing specification of the patent that would not enable/support the claimed matter completely. 
  3. Rejections (for example in United States: 35 U.S. Code 101, 102, 103 rejections) made during examination of the subject patent by the examiner and is subject to review by the Patent Trial and Appeal Board (PTAB). 
  4. Objections/ Opposition proceedings by third parties interested in re-examination during pre-grant/ Post-grant review of the patent. 
  5. Inter partes review (IPR) for challenging the claims of an issued patent wherein the interested party is completely involved in the proceedings. 

Common Prior Art Pitfalls

Not understanding the novelty correctly

Whenever performing an invalidity search, it is very important to correctly understand the novelty of the patent and how the present invention is different from background, what changes have been introduced and what are the effects of the changes. Incorrect understanding of novelty results in analysing and shortlisting incorrect references those might teach away from the invention. For correct understanding of the novelty, a thorough File History Analysis should be done and arguments between the examiner and the applicant should be read carefully. Further, the examiner also states the reason for allowance of claims. 

File History for patents of different countries are publicly available and can be accessed from the respective register sites of those countries. For example, for a US patent – USPTO patent center, for EP patent – EPO register, and so on. 

Incorrect claim interpretation

Before starting the invalidity search, searcher must be aware of the claim limitations and requirements. It is very important to read the claim in light of the specifications for a proper understanding of various possibilities that different embodiments specify. Not understanding the claim language often leads to performing a wrong prior art search. 

Deciding the search cut-off date

Generally, in invalidation search cases, the priority date of the subject patent is considered as the search cut-off date at first go. However, this is a wrong practice and might create a problem if relevant prior arts are overlooked due to incorrect cut-off date. 

In most cases, the earliest priority date/ earliest filing date is requested as the cut-off by the client. But, this is not true for example when the subject patent is a continuation-in-part application of a parent application. In such a case, there are high chances that a new matter has been added to the specification and claimed. So, instead of earliest priority date, the filing date of this matter becomes the search cut-off date for this newly claimed matter. 

Moreover, different jurisdictions have different laws regarding the date criteria for a patent to be rendered invalid. 

Focusing on Patent Literature Only

At times, a searcher is mainly focused on finding prior arts only in patent databases and gives little to no attention towards non-patent literature that might be very helpful otherwise. This may lead to missing relevant prior arts because:  

  1. The searcher might have missed an NPL such as a journal, white paper, research paper, thesis, dissertations, books, blogs, etc. 
  2. The searcher might have missed relevant products or product manuals existing prior to the search cut-off date. 
  3. The searcher did not pay attention to standard searching involving technology standards from various SSOs such as IEEE, ETSI, 3GPP, ANSI, Qi, TIA, ISO, and others. 

This is because patent databases like Questel Orbit, Patsnap, XLSCOUT, etc are very well maintained and forming a structured query on a patent database can be easier as compared to non-patent databases. Further, patent databases provide high quality filters like date criteria, country code, classification-based search, assignee based search, etc. moreover, there are many publications which are not available on the internet and in order to identify such prior arts, printed literature should be analysed by accessing physical libraries. 

To avoid this problem, XLSCOUT has come up with an AI and NLP based Non-patent Literature search tool as well as a standard search tool which provides the user with a list of potential non-patent prior arts. 

Identifying Grounds for Patent Invalidity - 8 Prior Art Pitfalls

Looking for 102(b) Prior Arts only!

An art is considered a valid prior art under US Patent law 102(b) iff the art was published one year prior to the earliest filing date of the subject patent. This kind of prior art is considered as the strongest in court of law if the art discloses all the elements of the claimed invention of the subject patent. 

However, such an art can be tricky to identify at times due to a gap of one year window. Thus, in an intention to identify a 102(b) prior art, a searcher might miss onto better arts falling under 102(a) or 102(e). Further, the searcher must keep in mind that two or more references can be combined and user for proving invalidity of a claimed matter under obviousness (103). 

A mix of prior art references should be shortlisted by the searcher covering all the aspects of the claim either independently or in combination with other references. 

Not using proper variations of keywords

A patent or patent application specification generally uses very limited variations of a keyword. For example, one inventor uses a term camera to denote a device capable of capturing multimedia whereas another inventor might use the term camcorder, videocam, ICD, etc to denote a similar device. As another example, one inventor uses the term “pilar” for protrusions of a semiconductor device whereas another inventor uses fingers, pillar, protrusion or simply raised portions. 

Often, searchers use only the keywords used in the subject patent for formulation of search queries while ignoring other possible synonyms of the word. However, all possible relevant variations of a word must be used while searching for a prior art to make sure that nothing is missed. To help with this problem, searcher can use dictionary, thesaurus, or XLSCOUT keyword helper

Identifying Grounds for Patent Invalidity - 8 Prior Art Pitfalls 3

Relying Only on the Claims of a Prior Art Patent

While mapping a prior art patent reference to the claims of the subject patent, entire specification of the prior art including, summary, abstract, detailed description, drawings must be considered to extract the relevant text in addition to the claims of the prior art. Using only claims for mapping purpose is a very incorrect practice. The text used could be present anywhere in the published prior art. 

Not using proper search platforms

Invalidating a patent requires vigorous searching not only on free databases such as google, google patents, etc but also on paid databases. These paid databases have a high volume of indexed patents from all over the world which are not otherwise freely available. Further, these databases also provide high level English translation for foreign non-English references and also provides a list of patents those are just recently published and are not accessible on free databases. Some of these databases are XLSCOUT, Questel Orbit, PatSnap, LexisNexis TotalPatent, etc.  

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