Patents, Property, and Prospectivity

60 Pages Posted: 20 Mar 2018 Last revised: 13 Jun 2019

See all articles by Jonathan S. Masur

Jonathan S. Masur

University of Chicago - Law School

Adam Mortara

Bartlit Beck Herman Palenchar & Scott LLP

Date Written: March 15, 2018


When judges change the legal rules governing patents, those rule changes are always retroactive. That is, they apply equally to patents that have already been granted and patents that do not yet exist. There are benefits to making a rule retroactive, particularly if the new rule is an improvement over what preceded it. But there are costs as well. Retroactive rule changes upset reliance interests. This can be particularly harmful when those reliance interests involve rights or entitlements that form the basis for substantial financial investment, as is often the case with patents. What is more, judges are aware that their decisions can do violence to existing reliance interests. This makes judges wary of changing patent rules in the first place, which can lead to the law becoming stultified. Reducing the rate of legal change is not an adequate solution. Neither is takings law, which is commonly applied to solve similar problems that arise in the context of real property but is a poor fit for intellectual property. Rather, to ameliorate the reliance concerns generated by legal change, federal judges should be afforded the latitude to make their rulings purely prospective. And patent judges should exercise this discretion in the many cases where forward-looking change is called for, but backwards-looking change will do more harm than good.

Keywords: patents, retroactive, prospective, habeas, grandfathering, federal circuit, reliance interests, investment, retroactivity, prospectivity, teague

Suggested Citation

Masur, Jonathan S. and Mortara, Adam, Patents, Property, and Prospectivity (March 15, 2018). Stanford Law Review, Vol. 71, p. 963 (2019), University of Chicago Coase-Sandor Institute for Law & Economics Research Paper No. 842, U of Chicago, Public Law Working Paper No. 659, Available at SSRN:

Jonathan S. Masur (Contact Author)

University of Chicago - Law School ( email )

1111 E. 60th St.
Chicago, IL 60637
United States
773.702.5188 (Phone)


Adam Mortara

Bartlit Beck Herman Palenchar & Scott LLP ( email )

Courthouse Place
54 West Hubbard Street
Chicago, IL 60610
United States

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