An Empirical Study of Patent Litigation Timing: Could a Patent Term Reduction Decimate Trolls Without Harming Innovators?

This Article conducts an empirical analysis of the relative ages of patents litigated by practicing and nonpracticing entities (NPEs). By studying all infringement
claims for a sample of recently expired patents, I find considerable differences in
litigation practices between these groups. Product-producing companies usually
enforce their patents soon after issuance and complete their enforcement activities
well before their patent rights expire. NPEs, by contrast, begin asserting their
patents relatively late in the patent term and frequently continue to litigate until
expiration. This variance in litigation timing is so dramatic that all claims assert-
ing the average product-company patent are resolved before the average NPE
patent is asserted for the first time. Further, I find that NPEs are the dominant
source of patent enforcement in the final few years of the patent term. NPEs,
enforcers of just twenty percent of all studied patents, are responsible for more than
two-thirds of all suits and over eighty percent of all infringement claims litigated in
the final three years of the patent term. These findings cast serious doubt on the
utility of the last few years of the patent term and suggest that Congress should, at a
minimum, consider increasing the frequency and magnitude of maintenance fee
payments in the latter half of the term.

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