Think Like a USPTO Examiner: A Look at the Patent Public Search Tool
A recent SOaR webinar sheds light on examiner search strategies
For intellectual property professionals and inventors, understanding how the examiner determines the novelty of an invention can be vital before and during the patent application process. The U.S. Patent and Trademark Office (USPTO) provides a free resource, the Patent Public Search (PPUBS) tool, that offers a window into the same search methodologies used by patent examiners. Leveraging this tool effectively can potentially improve the quality of a patent application and provide a clearer picture of the path to allowance.
The USPTO's Stakeholder Offerings and Resources (SOaR) program recently provided training to the public on how examiners approach searching, highlighting that a complete and thorough search is the fastest path to a quality examination. As the presenter noted, “The easiest Office Action to write is the one with the best references.” (SOaR Slides, p. 4).
The Foundation of a Complete Search
From the webinar, an examiner's search is built on a tripartite foundation, considering three essential sources for prior art. (p. 5) While PPUBS primarily focuses on the first, practitioners should be mindful of all three:
Domestic patent documents: This includes issued U.S. patents (USPAT) and pre-grant patent application publications (US-PGPUB).
Foreign patent documents: Art from patent offices around the world.
Non-patent literature (NPL): This broad category includes scientific journals, conference proceedings, books, dissertations, and web pages.
Examiners are instructed not to eliminate any of these sources "unless the examiner has and can justify a reasonable certainty that no references, more pertinent than those already identified, are likely to be found in the source(s) eliminated." (p. 5) This underscores the comprehensive nature of an official search. For practitioners, this is a point of caution.
While PPUBS is a significant step forward in public search capabilities, it does not replicate the full suite of internal databases available to examiners, which include extensive foreign patent and NPL collections. Therefore, a search in PPUBS, however thorough, should be considered a critical but not necessarily exhaustive part of a prior art investigation.
Strategizing the Search: Identifying What to Look For
Before diving into search queries, the speakers indicated that a strategic plan is necessary.
Examiners are taught to first identify the problem the applicant is trying to solve and then identify the features of the invention that provide the solution. (p. 11) This approach moves beyond simple keyword matching and focuses on identifying the inventive concept.
The webinar relayed that a key part of this strategy involves investigating related documents. This includes looking at other patents or applications filed by the same inventor or assignee. This can reveal previously cited art, offer insights into classification areas, and show how other examiners have approached similar subject matter. (p. 9)
Mastering the PPUBS Tool: Syntax and Operators
The PPUBS tool, accessible from the USPTO homepage, combines three databases: US-PGPUB (U.S. published applications since 2001), USPAT (all issued U.S. patents since 1790), and USOCR (optically recognized text of older patents).
To search like an examiner, one must understand the tool's syntax. PPUBS allows for field-specific searching using index abbreviations. For instance, to search for the word "golf" only in the title of a patent, the query would be: golf.ti.
A comprehensive list of these searchable index fields is available in the PPUBS "Help" section. Much of the power of PPUBS comes from combining keywords with Boolean and proximity operators.
Boolean Operators connect concepts:
AND: Requires both terms to be in the same document.
OR: Requires at least one of the terms to be in the document.
NOT: Excludes documents containing a specific term. (p. 20)
Proximity Operators define the spatial relationship between terms, which is critical for refining results:
ADJ[n]: Terms must be within 'n' words of each other, in the specified order, and in the same sentence.
NEAR[n]: Terms must be within 'n' words of each other in any order within the same sentence.
WITH: Terms must be in the same sentence.
SAME: Terms must be in the same paragraph.
Using these operators prevents the "noise" of finding keywords scattered unrelatedly throughout a long document.
For example, a search for (mouse OR rodent) SAME (trap OR cage) is far more targeted than (mouse OR rodent) AND (trap OR cage).
The SAME operator ensures the concepts appear in the same paragraph, making it more likely they are discussed in a related context.
The Mousetrap Example: Combining Text and Classification
The SOaR presentation used an example of a sophisticated mousetrap to illustrate search techniques. The invention involved a device with upper and lower compartments, multiple trapdoors, a bait area, and a sensor-controlled circuit to actuate the doors. (pp. 25-26).
A text search strategy would begin by brainstorming synonyms for the key concepts:
Animal: rodent, mouse, mice, vermin, critter, insect, cockroach.
Trap: cage, mousetrap.
Door: trapdoor, "false floor", hatch.
Sensor: ultrasonic, detector.
These synonyms are then combined using operators. A "broad to narrow" approach might start with a general concept, like (rodent or mouse) WITH (trap or cage), and progressively add limitations, such as L1 AND (trapdoor or hatch) AND (sensor or ultrasonic).
However, a text-only search is rarely sufficient. As the USPTO notes, "It is rare that a text search alone...will constitute a thorough search." (p. 28).
Classification searching is essential, particularly in mechanical arts where functionality can be described with varied terminology.
For the mousetrap example, the relevant Cooperative Patent Classification (CPC) is A01M 23/00 ("Traps for animals"). Within this main group, there are more specific subgroups, such as:
A01M 23/02: Collecting-traps.
A01M 23/10: with rotating cylinders or turnstiles.
A01M 23/12: with devices for throwing the animal to a collecting chamber.
Because the invention uses an ultrasonic sensor, an examiner would also search in analogous arts, such as G08B 13/16, which covers alarm systems actuated by interference with mechanical vibrations, including ultrasonic detection.
The most effective strategy is an iterative mixing of text and classification searches. A practitioner might start by searching within a relevant CPC class and then use keywords to filter the results.
For instance: A01M23/12.cpc. AND (sensor or detector). This apparently focuses the search on throwing-style traps that also mention a sensor, yielding highly relevant results that a broad text search might miss.
Cautions and Benefits for Practitioners
Adopting an examiner's search methodology offers clear benefits. It allows for the discovery of better prior art earlier in the process, enabling the drafting of more resilient claims. It can provide a realistic assessment of an invention's patentability and can help manage applicant expectations.
However, IP professionals should remain cautiously aware of the limitations. The search process is complex and has a steep learning curve. Overly broad searches can generate thousands of irrelevant results, while overly narrow "home run" searches have a low chance of success and are not comprehensive.
Most importantly, PPUBS is not a perfect mirror of an examiner's toolkit. The absence of comprehensive, easily searchable foreign patent and NPL databases means that a "clean" search in PPUBS does not guarantee a smooth examination.
Ultimately, searching is a dynamic and iterative process. Technology and its associated "buzzwords" are constantly in flux. By understanding the principles of a complete search, e.g., using the PPUBS tool, IP professionals may be able to elevate their practice, conduct more effective prior art analyses, and better anticipate the examination process.
Disclaimer: This is provided for informational purposes only and does not constitute legal or financial advice. To the extent there are any opinions in this article, they are the author’s alone and do not represent the beliefs of his firm or clients. The strategies expressed are purely speculation based on publicly available information. The information expressed is subject to change at any time and should be checked for completeness, accuracy and current applicability. For advice, consult a suitably licensed attorney and/or patent professional.