Behind the Patent's Veil: Innovators’ Uses of Patent Continuation Practice, 1975-2002
Graham, Stuart J. H.
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This paper employs new data on the use by patentees of continuation applications in the United States from 1975-2002 to shed light on patentees' motivations for and actual uses of the continuation application procedure, a procedure available only in the U.S. which allows a patent applicant to voluntarily delay issue of a patent. The paper investigates the affect that continuation use has had upon patent grant lags, evaluating whether routinely used research methods that ignore continuation delays may be improved by accounting for continuations in patents' application lineage. This paper demonstrates conclusively that a sizeable share of patent applicants employs the continuation, that continuation use by patent applicants results in substantial additional delay in the time-to-grant statistics for associated issued patents, and that significant changes in the pattern of continuation use have occurred since Congress enacted legislative amendments intended to curb the procedure’s use. Evidence provided in this paper supports a contention that the continuation has been economically important in shaping the environment for innovation, influencing industrial organization, and social welfare. The paper also demonstrates that continuation practice is common in overall US patenting, and that in some important sectors, including electronics, computing, pharmaceuticals, chemicals, and biotechnology, a substantial minority, and in some instances a majority of patents in recent years have issued with continuation in their application lineage. Furthermore, substantial intersectoral differences are shown in innovators’ use of the continuation, as well as significant changes in the patterns of usage over time.