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Sturm College of Law


Invention, Claim limitations, Patent law


Based on the landmark 1961 Supreme Court decision, Aro Manufacturing Co. v. Convertible Top Replacement Co., the long held wisdom in patent law has been that there is no heart or gist of the invention. In other words, patent law does not attribute any special significance to a particular subset of claim limitations regardless of how important those limitations are. Under Aro, judges and juries are told that they need to view all the limitations, even stock components, with equal significance. They must resist focusing on the heart of the invention when making any decision.

Aro’s commandment has spread far beyond the doctrine of repair and reconstruction, the subject matter of Aro. In fact, it has become a basic tenet of patent law and has been adopted by the doctrines of infringement, anticipation, obviousness, and the written description requirement. To this day, judges and commentators continue to cite to Aro and proclaim that patent law does not recognize the heart of the invention.

This Article challenges the conventional wisdom as neither accurate nor wise. It is not accurate because other doctrines unwittingly consider the heart of invention while using different nomenclature. For example, the doctrines of contributory infringement and inequitable conduct do not openly challenge Aro, yet they rely on the “material part of the invention” and “point of novelty” respectively. Aro’s commandment is unwise because a rule against considering the heart of the invention is bad policy. On a purely intuitive level, it is entirely sensible for judges and juries to focus on the heart of the invention in making their decisions. This Article demonstrates why this intuition is correct by analyzing how different patent law doctrines rightly and wrongly rely on the heart of invention.

The Article then provides a framework for determining when the heart of the invention should and should not be considered. Applying this framework to various areas of patent law, this Article explains: 1) why the fifty years of jurisprudence in the doctrine of repair and reconstruction is wrong; 2) why the heart of the invention may be a permissible consideration in various developing areas of patent law including subject matter patentability; and 3) how the Supreme Court got it “almost” right in Quanta Computer, Inc. v. LG Electronics, Inc., when it decided that the “essential features” (another pseudonym for the heart of the invention) was an important consideration within the doctrine of patent exhaustion.

Publication Statement

Originally published as Bernard Chao, Breaking Aro's Commandment: Recognizing That Inventions Have Heart, 20 Fordham Intell. Prop. Media & Ent. L.J. 1183 (2010). Copyright is held by the author. User is responsible for all copyright compliance.