Search and you shall find [naught, you hope]

By Jacob Drory


My previous posting (Sept. 9) elaborated on the novelty and unobviousness criteria of patentability, both assessed by the Patent Office in consideration of what has already been known in the field of the invention and in related fields—the “prior art”.  Although technically an applicant is not required to conduct a prior art search , only to “describe the background art that, as far as is known to the applicant, can be regarded as important for the understanding, searching and examination of the invention”, since prior art which puts into question the novelty or unobviousness of an invention may invalidate any pending patent application filed in respect of the invention or any patent issued from it, it is prudent to thoroughly search the prior art before a commitment is made to the protracted and costly pursuit of a patent, as the endeavour may thus prove futile at the outset.  With millions upon millions of issued patents and published applications worldwide and a vast and rapidly growing corpus of technical literature the probability that one’s inventive concept has already been brought to light somewhere in some form must not be underestimated.

An additional and equally important reason to conduct a thorough prior art search is to ascertain that the manufacturing and selling of an invention would not infringe on any patent in force.  This situation arises when an invention incorporates or improves on patented technology.  Although the existence of a patent for one or more (but not all) elements of an invention does not necessarily affect its patentability, while the patent is in force a license to manufacture and incorporate the patented technology must be obtained from the patent owner to avoid infringement.


Prior art comprises printed or electronic publications (e.g. periodical articles, technical papers, theses, textbooks, and websites), oral expositions (e.g. conference presentations, lectures, or informal exhibitions), issued patents (in-force or expired), and pending applications open to public inspection.  Exceptionally, unpublished pending applications are part of the prior art as well.  In view of the vast amount of non-patent technical publications worldwide, and of the practical limitation in finding and accessing much of this literature, a truly exhaustive search of the prior art is clearly impossible.  In practice, therefore, prior art search—whether conducted by the inventor, a patent search professional, or the Patent Office—is focused almost exclusively on issued patents and published patent publications.

Preliminary search

A reasonably thorough search of the patent literature may (and should) be conducted by the inventor using the plethora of freely-accessible, web-based search tools that are now available.  Issued patents and published applications may be searched on patent databases that are maintained by official patent authorities around the world, most importantly: the United States Patent and Trademark Office (USPTO) PatFT full-text database, the European Patent Office (EPO) espacenet database, and the World Intellectual Property Organization Patentscope databse.  The Canadian Intellectual Property Office (CIPO), as most other large patent offices, maintains a national patent database.  In addition to the official patent databases, several online patent search engines are also available.

Non-patent literature may be searched online to a lesser extent, using ordinary Internet searching tools and techniques.  Ideally, other sources of technical information should be searched as well, including textbooks, periodicals, product catalogues, conference proceedings, theses, and other research and  technical papers—materials which can be found in many public reference libraries and in university libraries—but for obvious practical reasons, as discussed above, such a search is of very limited scope and, hence, utility.

A more efficient search is possible by visiting the Patent Office in person.  The Client Service Centre (CSC) of the Canadian Intellectual Property Office (CIPO) provides a direct interface to the CIPO and USPTO patent databases and search tools, which is faster and provides greater functionality than the Internet interface of these databases.  One must be prepared and able, however, to devote the necessary time to learning how to use these tools effectively.

Professional search

Failure to identify relevant prior art through a preliminary search must not be construed as evidence of its absence.  Due to limitations in the capability of the freely-available web-based search tools, significant prior art may well be missed.  Unless prior art is found, during the preliminary search, which fully “anticipates” the invention (i.e. discloses each of its elements), thus rendering it unpatentable, it is highly advisable to turn the matter to a patent search professional.

Professional patent searchers subscribe to fee-based commercial patent databases which allow a far more effective search to be performed.  These databases are interrogated with sophisticated query languages and are interfaced with powerful tools, allowing a most efficient, highly organized and thorough search.

A patent search conducted with any of the free, web-based tools typically yields dauntingly voluminous data.  Sifting through seemingly endless patent documents is an onerous, time-consuming task which can be quite demoralizing.  This, inevitably, affects the quality of the search.  Professional patent searchers are armed with highly expressive query languages with which they skillfully formulate complex queries to minimize spurious hits.  Through training and experience, professional searchers are then able to quickly scan the resulting data, while keeping a critical eye for pertinent information.

It has also been argued that searching for something one is hoping never to find tends to cloud one’s eye and blur one’s perception.  An impartial, experienced, professional searcher is free from such bias and is less likely to overlook pertinent material.


Many of the Internet-based, free patent databases have limited coverage of early patents.  For inventions in newer fields of technology, this is not an impediment, but for simple, mechanical inventions it is important to have access to the earliest recorded patents.

Pending patent applications are held in confidential status for 18 months following their filing date.  During this period, patent applications do not appear on public searches of patent databases.

Due to the sheer amount of technical information now available, no patentability search – by whichever means and however careful – can purport to be truly exhaustive.  The possible existence of an obscure publication which fully anticipates one’s invention is ever-present.  Prior art searches conducted by examiners at the patent office are also far from exhaustive.  Consequently, an application may be allowed on occasion, while relevant yet undiscovered prior art exists.  This is not at all as “fortunate” as it may first appear, as the missing relevant prior art may later haunt the patentee in court, if the patent is wielded by its owner against an infringing party.  In this case, the first line of defense is often an attempt to invalidate the issuance of the patent on grounds of lack of novelty or obviousness following a very thorough prior art search.  Should significant, hitherto undiscovered prior art be unearthed, this may result in the revocation of the patent (and, of course, in dismissal of the infringement suit).


With the present day vast and growing number of patents and other technical publications, since any one such publication may potentially render an application or a patent invalid, it is highly advisable to conduct as thorough a search of the patent and technical literature as practicable.  An in-depth search of in-force patents in the field of an invention is also necessary to avoid infringement.  A preliminary search by the inventor followed, if necessary, by a professional search is the recommended course of action.


Jacob Drory is the founder and principal operator of Consolidated Patentwrights, a unique non-profit service offering a complete online solution to independent inventors. A prolific inventor himself, Jacob is a McGill University physics graduate, a former commercial pilot, and has worked for a number of years in courseware development, creating instructional content and technical illustrations, and programming interactive components.


This document reflects the author’s own perspective on the matter. It does not constitute legal counsel, nor does its inclusion in this blog imply an endorsement of these views by the Canadian Innovation Centre.