Neilson v. Harford: Shape and Form in Patent Law
Forthcoming, Research Handbook on Creativity, Entrepreneurship, and Intellectual Property: Comparative Perspectives on Forgotten Legal Lore
35 Pages Posted: 22 Jan 2020 Last revised: 16 Jun 2020
Date Written: January 9, 2020
Neilson v. Harford has cast a long shadow over patent law. For American courts in the nineteenth century, the 1841 case from the Court of Exchequer was an authority whose “correctness has never been doubted and denied.” More recently, Neilson served as the ostensible authority for some of the Supreme Court’s most significant changes to the doctrine of patent eligibility under § 101. Parker v. Flook took from Neilson the notion that fundamental principles cannot contribute to the patent-eligibility of a claim, and Mayo v. Prometheus relied on Neilson to support its requirement for unconventional application of new discoveries.
Drawing on a complete account of the Neilson trial that has never been examined by legal scholars, this chapter shows that the true story of Neilson v. Harford is very different than the one told by the Supreme Court. The Court of Exchequer never treated fundamental principles as part of the prior art, nor did it require inventive application of new discoveries; Neilson’s patent was sustained largely because discovery required only well-known, routine, and conventional means for application. The central question in Neilson was to what extent Neilson’s invention – and by extension patents in general – were bound by shape and form.
The Exchequer’s conclusion that Neilson’s patent transcended form was key to three of the Supreme Court’s foundational nineteenth century cases: Winans v. Denmead’s extension of infringement beyond the patentee’s embodiment; Tilghman v. Proctor’s separation of a process from its instrumentalities; and O’Reilly v. Morse’s delineation of the outer bounds of enablement. In particular, the Morse Court’s contrast between Neilson’s invention and Morse’s illustrates that Morse was based on conventional enablement reasoning, not on the unpatentability of scientific discoveries.
Keywords: patent law, patent eligibility, Neilson v. Harford, hot blast
JEL Classification: O34
Suggested Citation: Suggested Citation