Is common sense good enough to make up for deficiencies of a cited reference in an obviousness analysis? In Arendi S.A.R.L. v. Apple Inc., the Federal Circuit said “no,” by reversing a decision of the Patent Trial and Appeal Board (“PTAB”) to invalidate U.S. Patent No. 7,917,843 (the “Arendi patent”).

When Arendi S.A.R.L., a Luxembourg company, brought patent infringement suits against several technology heavyweights, including Apple, Inc., Google, Inc., and Motorola Mobility LLC, these defendant companies struck back by filing a petition for an Inter Partes Review (“IPR”) seeking to invalidate the Arendi patent. In the IPR proceeding, the PTAB invalidated the Arendi patent on the grounds of obviousness under 35 U.S.C. §103. Arendi then appealed the case to the U.S. Court of Appeal for the Federal Circuit.

The Arendi patent is directed to computer functions that allow a user to remain in a document displayed by a first computer program while accessing and conducting a search using a second computer program. In particular, independent claim 1 of the Arendi patent recites, in part:

“performing a search using at least part of the first information as a search term in order to find the second information, of a specific type or types, associated with the search term in an information source external to the document, wherein the specific type or types of second information is dependent at least in part on the type or types of the first information.”

During the IPR proceeding, U.S. Patent No. 5,859,636 to Pandit (the “Pandit reference”) was cited as the sole prior art against the Arendi patent under a 35 U.S.C. §103 obviousness rejection. The Pandit reference teaches recognizing different classes of text, such as telephone numbers, in a document and providing suggestions based on the type of text class. Although the PTAB recognized that the Pandit reference fails to teach the step of performing a search, as recited above in claim 1 of Arendi patent, the PTAB ruled that, as a matter of common sense, it would have been obvious to one of ordinary skill in the art to utilize a computerized search with the teachings of the Pandit reference. Thus, the PTAB essentially made up for the deficiencies of the Pandit reference using what it believed to be common sense to one of ordinary skill in the art. In doing so, the PTAB rejected Arendi’s argument that common sense can only be applied when combining references that disclose all the required limitations.

On review, the Federal Circuit considered whether the PTAB had misused common sense in this case to make up for the missing limitation in the prior art. While the court affirmed that common sense can and should be used in an obviousness analysis, the court set forth three “caveats” to consider when applying “common sense” in an obviousness analysis:

1. Common sense is typically used to provide a known motivation to combine, not to supply a missing claim limitation;

2. In a rare case that common sense is used to supply a missing limitation, the missing limitation is usually simple and the technology particularly straightforward; and

3. Common sense cannot be used as a wholesale substitute for reasoned analysis and evidentiary support.

Based on expert witnesses and other evidence, the court acknowledged that the broader notion of searching for data in a database is indeed common sense. However, in this case, the court found that there was simply inadequate reasoning and explanation on why and how it would have been obvious to modify the Pandit reference based on the general common sense to arrive at the specific search step recited in claim 1 of the Arendi patent. For example, the court stated that: “Appellees have failed to show why it is proper to extrapolate from this general background knowledge of searches in a database to add a search for a telephone number to the Pandit reference.” In the absence of clear reasoning and explanation, the court concluded that the application of common sense fails to meet the burden of establishing unpatentability of the Arendi patent on obviousness grounds. Accordingly, the decision of the PTAB that invalidated the Arendi patent was reversed by the court.

While common sense is useful, and sometimes essential, in living out one’s daily life, the Arendi decision taught us that common sense should be applied cautiously in an obviousness analysis of a patent. In particular, common sense should rarely be used to supply a missing limitation. And, in the rare cases that common sense is used to supply a missing limitation, it should be accompanied with reasoning and explanation detailing why and how the common sense can be applied to modify the cited reference to arrive at the missing limitation.

In general, when there are deficiencies in a cited reference, patent practitioners seeking to establish obviousness rejections would be better off providing additional references to address the deficiencies, rather than relying solely on common sense to bridge the gap between the cited reference and the claim in question. The Arendi decision is a good example of how, without concrete reasoning and explanation, the court tend to view the use of common sense simply as “hand-waving” explanations that reflect a lack of diligence on the part of the patent practitioner. There is simply no excuse for sloppiness in the practice of law; and that, we know, is just common sense.