The "Evergreening" Metaphor in Intellectual Property Scholarship

68 Pages Posted: 20 Feb 2020 Last revised: 10 Aug 2020

See all articles by Erika Lietzan

Erika Lietzan

University of Missouri School of Law

Date Written: February 12, 2020


This article is a plea for changes in the scholarly dialogue about “evergreening” by drug companies. Allegations that drug companies engage in “evergreening” are pervasive in legal scholarship, economic scholarship, medical and health policy scholarship, and policy writing, and they have prompted significant policymaking proposals. This Article was motivated by concern that the metaphor has not been fully explained and that policymaking in response might therefore be premature. It canvasses and assesses the scholarly literature — more than 300 articles — discussing or mentioning “evergreening.” It catalogues the definitions, the examples, and the empirical studies. Scholars use the term when describing certain actions taken by the innovative companies that develop and introduce new medicines to market. But they are inconsistent in their descriptions of the circumstances to which the term applies. And though most claim the innovator has “extended” something in these circumstances, they do not agree on the particulars. The literature is similarly in disarray about what has been “evergreened” — an invention, a product, a price, a patent, or something else entirely. All of this makes it hard to know from the literature what exactly scholars are writing about. After sorting through the definitions and examples — and considering the legal framework and practical landscape in which drug innovators and their generic competitors operate — this Article offers an answer and, more importantly, identifies the implicit normative claim. In simple terms the normative claim in the literature is something like this: “an innovator should not enjoy an exclusive market and supra-competitive pricing for innovations that stem in some fashion from a separate innovation for which it already enjoyed a 20-year patent term. Or at least, a drug innovator should not.” This Article does not defend, or reject, this normative claim. Instead, it makes a different claim: that policymaking should be based on descriptive scholarship that is careful and precise about the relevant law and facts, normative work that is clear and candid about its claim and thorough in its reasoning, and empirical studies that document the actual problem the normative proposals and policymaking proposals are meant to address. Significant policymaking would be premature today, because we have not yet produced this body of work. Constant use of the “evergreening” metaphor may be obscuring this failure. The Article concludes with recommendations for scholars continuing to work on these topics, focusing on ways that we can provide quality work to assist policymakers considering the normative claim.

Keywords: drugs, patents, generic drugs, FDA, evergreening, antitrust

Suggested Citation

Lietzan, Erika, The "Evergreening" Metaphor in Intellectual Property Scholarship (February 12, 2020). 53 Akron Law Review 805 (2019), University of Missouri School of Law Legal Studies Research Paper No. 2020-08, Available at SSRN:

Erika Lietzan (Contact Author)

University of Missouri School of Law ( email )

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