Fletcher YoderSeparate patentability of allegedly infringing equivalent of an invention of a patent in suit does not require patentee to prove infringement under doctrine of equivalents by clear and convincing evidence, but rather by a preponderance of evidence.
Congress specified the applicable standard of proof for an invalidity defense in 1952 when it codified the common-law presumption of patent validity. Specifically, a patent is presumed valid unless proven invalid by clear and convincing evidence.
Where the non-moving party (patentee) bears the burden of proving infringement, in a motion for summary judgment nothing more is required than the filing of a summary judgment motion stating that the patentee had no evidence of infringement and pointing to the specific ways in which accused systems did not meet the claim limitations.