I. THE DOCTRINE OF EQUIVALENTS: FROM FAIRNESS TO FRICTION
A. THE NORMATIVE BASIS OF PATENT LAW SHIFTS FROM FAIRNESS TO EFFICIENCY
Two related notions of fairness have dominated legal thought about patents
for much of the history of American patent law. First, an inventor deserves a
property right in her invention as a reward for her labor.33 And second,
competitors should not unjustly enrich themselves by using a patented invention
without permission.34 Nineteenth century judges, particularly during the first
half of the century, construed patent law “benignly in favour of patentees,”35
and viewed the inventor as having a natural property right in his invention.