Do a Patent Search Before Starting the Application

Before the expense of preparing and filing a patent application is incurred, a patentability search is ordinarily advisable. Such a search will disclose whether any existing patent anticipates the invention or any combination of patents would make the invention obvious to one skilled in the art (i.e., “prior art”).  Information about the applicable prior art can be used to make the threshold determination as to whether or not additional resources should be invested in applying for a patent and is also a valuable tool for drafting the strongest possible patent application.  There are obviously significant costs associated with conducting an extensive patentability search and the most common approach is to limit the scope of the search to issued patents and to relevant pending patent application that have been published.  This not only reduces the expense of the search it is also in line with the volume and type of work that the examiner of the application will eventually do since examiners typically limit their own search activities to issued patents.  If the applicant can identify the frame of reference that the examiner is likely to use it is easier to craft disclosures in the application that anticipate issues that might be raised by the prior art.


Although collections of United States patents or patent abstracts are maintained by some libraries around the United States, patents typically are not arranged by subject matter or otherwise conveniently indexed, which prevents a thorough search from being made. Accordingly, the search should be made at the PTO’s offices in Arlington, Virginia, which has a public search room where all of the patent issued by the United States have been classified according to an elaborate classification system which includes several hundred major classes, with possibly several hundred subclasses within each major class.  Many of the patents are cross-referenced into a number of subclasses. In addition, the PTO offers online access at its website to separate bibliographic and full-text patent databases.  The full texts of patents issued after 1976 are available at the website and can be searched, as can application filed after March 15, 2001.  Unfortunately, while earlier patents can also be viewed at the website and searched by number and current United States classification, it is not possible to do a full text search.  This can be an important limitation, which also applies to other websites that also provide time-limited patent databases, since there are often disclosures in older patents that can have a significant impact on the patentability of a new invention.

While inventors wishing to conduct their own searches can do so using the resources described above, the complexity of the classification system deployed by the PTO makes it extremely difficult to persons lacking the necessary experience to perform a sufficiently extensive search of the prior art.  In addition, some knowledge and understanding of the patent laws is necessary in order for the search to be an effective tool in determining whether or not the prospective invention has a good chance of winning a patent.  For these reasons, therefore, it is recommended that inventors engage the services of someone who is an experienced professional patent searcher located at the PTO.  Normally, a patentability search is conducted by the patent attorney sending a description of the invention to the patent searcher. The patent searcher will look through the patents in the relevant subclasses and present the patent attorney with the more pertinent patents. From this information, the patent attorney can give an opinion as to what feature or features might be patented and some estimate of the probability of obtaining patent protection.

The PTO search is a fairly good indicator of patentability. However, if the invention is of sufficient importance, a broader search may be in order. For example, it might be desirable to search the technical literature to ascertain whether the invention has already been disclosed in some technical article even though it has never appeared in the patent literature. Also, it might be advisable to extend the patent search into published foreign or international patent applications. This is commonly done by conducting what is called an “international search” at the Patent Office at The Hague, where the patents of a number of nations are on file.


The content in this post has been adapted from material that will appear in Technology Management and Transactions (Fall 2008) and is presented with permission of Thomson/West.  Copyright 2008 Thomson/West.  For more information or to order call 1-800-762-5272.

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