The objection is that the public should be able to fully rely upon the literal language of patentee's claims in order to understand the metes and bounds of the patentee's claimed invention. The doctrine of equivalents, by stark contrast, allows judges to rule that differences between the allegedly infringing product and patentee's claims merely amount to differences in "form only." However, when exactly is an accused product merely different in form than a claimed invention, and when is it different in substance? With the doctrine of equivalents, the answer to this question depends upon a judge's subjective determination.
A second, related objection to the doctrine of equivalents is that this can have a chilling effect on innovation. Many designers who would ordinarily design around a patent are now frozen in their tracks due to possible subjective expansions of claims. As a result, research into the development of potentially valuable alternatives that could add significant amounts of wealth to society do not ever get green-lit, out of fear of patent liability.
One judge even commented that nothing could be "more mischievous, more productive of oppressive and costly litigation, or exorbitant and unjust pretensions and vexatious demands" than relaxation of the requirement that patentees be bound by definite claims. Winans vs. Denmead, 56 U.S. 330, 343 (1853).
A second, related objection to the doctrine of equivalents is that this can have a chilling effect on innovation. Many designers who would ordinarily design around a patent are now frozen in their tracks due to possible subjective expansions of claims. As a result, research into the development of potentially valuable alternatives that could add significant amounts of wealth to society do not ever get green-lit, out of fear of patent liability.
One judge even commented that nothing could be "more mischievous, more productive of oppressive and costly litigation, or exorbitant and unjust pretensions and vexatious demands" than relaxation of the requirement that patentees be bound by definite claims. Winans vs. Denmead, 56 U.S. 330, 343 (1853).