Claim Construction – The US Patent Classification Glossary

This post may be helpful to those of you who litigate patent cases.  While it is true that the most significant sources of claim construction evidence are the claim language, specification, and file history, courts often consider reliable sources of extrinsic evidence such as technical dictionaries and glossaries.  In Phillips the Federal Circuit held that “Because dictionaries, and especially technical dictionaries, endeavor to collect the accepted meanings of terms used in various fields of science and technology, those resources have been properly recognized as among the many tools that can assist the court in determining the meaning of particular terminology to those of skill in the art of the invention.”  Phillps v. AWH Corp., 415 F.3d 1303, 1318 (Fed. Cir. 2005).  Thus, it is often the case that litigators will scour available dictionaries to find definitions that are helpful to their claim construction positions.

I recently came across “The US Patent Classification Glossary” on the U.S. Patent & Trademark Office website.  This glossary provides a list of definitions for the key terms that the PTO uses to categorize patents and patent applications.  I quickly located definitions for terms that had come up in my practice, such as “antigen,” “cover,” “signal,” and “layer.”  Based on a brief search, I was unable to find any published decisions discussing the glossary.  Thus, it is unclear whether litigants have previously attempted to rely on it or not.  Nevertheless, because these definitions are used by the Patent Office itself in determining how to classify patents, it could be persuasive to a court.  You may want to consider consulting it for your next case.

The glossary can be found at