Should Patent Infringement Require Proof of Copying?

Michigan. Law Review, Vol. 105, p. 1525, 2007

12 Pages Posted: 5 Jan 2007 Last revised: 25 May 2014

Date Written: January 4, 2007


Patent law gives patent owners not just the right to prevent others from copying their ideas, but the power to control the use of their idea even by those who independently develop a technology with no knowledge of the patent or the patentee. In an important paper, Samson Vermont challenges this received wisdom, arguing that independent invention should be a defense to patent infringement, just as it would be in copyright or trade secret cases.

Independent invention has much to recommend it. The most significant problem facing the patent system today is the rise of so-called "patent trolls" - entities who do not manufacture products or transfer technology, but wait and assert patents against successful companies who independently developed and manufactured the technology without knowledge of the patent. An independent invention defense would eliminate the troll problem in one fell swoop. Nonetheless, I have concerns. While I agree with Vermont that we can learn a great deal from the fact of independent invention, I am not yet persuaded that we can be sure that an independent invention defense will have no undue effect on incentives. Complicating this difficult empirical question is the likelihood that the effects of an independent invention defense would be different in different industries. Further, an independent invention defense will significantly change any market for patent rights that might exist or be developing today.

In light of this, I suggest four steps we might take that take advantage of Vermont's insights without moving all the way to an independent invention system. First, we should change the definition of willful infringement to exclude independent inventors. Second, we should adopt some form of a prior user right. Third, we should give simultaneous invention greater credence in determining whether inventions are obvious. Finally, we might consider whether the defendant independently invented as a factor in deciding whether to grant injunctive relief and the conditions to impose on such relief.

Suggested Citation

Lemley, Mark A., Should Patent Infringement Require Proof of Copying? (January 4, 2007). Michigan. Law Review, Vol. 105, p. 1525, 2007, 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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