Going to the ends of the earth to kill a patent – without breaking the bank

February 24, 2015

Michael N. Rader

(as published in Inside Counsel)

Are patents inherently vulnerable to invalidation? On one hand, the old adage — that inventors stand on the shoulders of their predecessors — seems like a virtual shorthand for the obviousness doctrine in patent law. Yet, on the other hand, patents enjoy a presumption of validity in court because the Patent Office is presumed to have evaluated them properly in light of the available information. Given that presumption, which juries tend to credit, it is the prior work that an inventor did not build upon — indeed, that which the inventor and the Patent Office did not even know about — that is most likely to lay the foundation for a successful challenge to a patent’s validity. This article provides four tips for locating such superior prior art on a budget.

Pursue concepts and innovators, not keywords

Too often, prior art investigations begin and end with database keyword searches focused on the words used in the asserted patent and its claims. One inventor’s technical lexicon may not, however, be representative. Keywords are therefore inherently limited. Keyword searches also tend to be expensive because they often yield a large number of references that must be evaluated by someone with detailed knowledge of the case.

A better strategy, though it requires a higher degree of technical expertise, is a more targeted search based on relevant technical concepts (rather than keywords). As prior art references addressing those concepts are located, the search focuses on their authors, co-authors, endnotes and forward citations. Authors of the more interesting references should be contacted and, if possible, retained as consultants to provide further input on where else to look. Retaining multiple experts as prior art search consultants can be a useful shortcut and need not be costly. An expert can generally identify the additional research avenues known to him or her with just a few hours of effort. Thus, for a modest cost, one can gain access to the collective wisdom of several experts who have been working in the relevant field for years.

Look beyond patents and mainstream journals

Many prior art searches focus on patent literature and mainstream journals because it is easy to search patent office websites and academic databases with keywords. The conceptual approach, however, often yields valuable materials that cannot be found with keywords. For example, conference abstracts and poster presentations often are not catalogued in databases but do exist in hard copy. Searching such materials is not as burdensome as many people assume. For example, it is usually straightforward to identify the annual conferences that are most germane to a particular technical area, and the proceedings of those conferences during the relevant years can be obtained from the sponsoring organization or even at a local university library. I have found outstanding prior art in this fashion at modest cost to clients.

In one case, the trail of scholarship related to a medical method patent led to surgical guidelines published by the Russian Ministry of Health in the 1970s. We obtained the guidelines booklet from the Russian State Library and brought a librarian to trial to authenticate it. That booklet helped us invalidate key claims of a competitor’s patent.

Don’t forget physical prior art

Sometimes the best prior art is a product (such as a device that was sold or used publicly in the United States) rather than a printed publication such as an article or a patent. In one recent case, the patent claimed a combination of features that were usually described separately — some innovators focused on and wrote about one component, while others described the second, even though the two were, in practice, intended to be used together. Thus, the paper prior art led primarily to obviousness combinations. A prototype product, however, demonstrated by our Japanese client at a trade show in the United States more than a year before the patent was filed, included both components. Finding a two-decades old device (and corroborating documents) in Japan was not easy but was well worth the effort and helped force a favorable settlement.

In another recent case, we noticed that prior defendants sued on the asserted patents had relied upon a user manual for a prior art Microsoft software product. We chose instead to rely on the product itself, which demonstrated the relevant functionality even more clearly than the manual. With screen shots and packet traces, we were able to show anticipation of the asserted patents, and the patent owner dropped its case with less than two weeks left before trial.

Turn the infringement contentions around

A final lesson is not to focus exclusively on what you believe the asserted patent claims actually cover. When the plaintiff stretches its patent claims to cover an accused product that you believe is far afield from the true claim scope, don’t hesitate to use the plaintiff’s contentions against it by searching for prior art that looks like the accused product. In fact, in several recent cases, we realized after some digging that the accused products themselves were, in relevant respects, described or offered for sale before the asserted patent was filed. The patentee’s infringement contentions had, therefore, effectively accused the prior art of infringing.


A wise person once said that cases are won and lost by strong detective work long before they hit the courtroom. That observation certainly applies to patent cases, in which defendants may quite literally have to bring prior art from the ends of the earth. While that sounds like a tall task, with appropriately focused search strategies, such prior art can be located and developed without breaking the bank.