Inducing Patent Infringement

27 Pages Posted: 28 Jul 2005


It is a fundamental principle of patent law that no one infringes a patent unless they practice the complete invention. Nonetheless, patent courts have long recognized that focusing only on the party who actually practices the invention will sometimes let off the hook the party who most deserves to be held liable. Thus, for over a century patent courts have extended liability to one who does not himself infringe, but who actively induces infringement by another. Since 1952, this principle has been enshrined in section 271(b) of the patent statute. As an idea, it has proven uncontroversial. Surprisingly, however, despite the venerable nature of inducement in patent law, the actual content of the inducement requirement has remained something of a mystery. In particular, courts have proven unable to decide two fundamental issues - what it means actually to induce infringement, and what the inducer must know and intend in order to be liable for acting. Though the United States Court of Appeals for the Federal Circuit, which was created in 1982, now handles all patent appeals, it has not brought uniformity to either issue. Indeed, there are Federal Circuit opinions taking diametrically opposed positions on the law of inducement. This confusion is doubly unfortunate given that the Supreme Court has recently imported the law of inducement from patent into copyright law. Before we adopt the concept of inducement in copyright cases, it would seem helpful to know what exactly it means in patent cases. In this article, I set out the fundamental disagreements among the courts as to the conduct and intent prongs of inducement. I explore the policies behind inducement law, and suggest that these disagreements can best be resolved not by picking one side or the other, but by thinking of inducement as a sliding scale inquiry in which a more specific intent to infringe is required to find liability if the defendant's conduct is otherwise less egregious. This resolution not only makes policy sense, and integrates section 271(b) with the rest of the statute, but it may even have the virtue of explaining most of the apparently conflicting caselaw. Application of this sliding scale approach also has implications for secondary liability in copyright law.

Suggested Citation

Lemley, Mark A., Inducing Patent Infringement. UC Davis Law Review, Vol. 39, p. 225, 2005, Stanford Law School, Public Law Working Paper No. 110, Available at SSRN:

Mark A. Lemley (Contact Author)

Stanford Law School ( email )

559 Nathan Abbott Way
Stanford, CA 94305-8610
United States

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