What is the legal effect of a reissued patent on patent term extension?
The legal effect of a reissued patent on patent term extension is governed by 35 U.S.C. 252, which states:
“The surrender of the original patent shall take effect upon the issue of the reissued patent, and every reissued patent shall have the same effect and operation in law, on the trial of actions for causes thereafter arising, as if the same had been originally granted in such amended form, but in so far as the claims of the original and reissued patents are substantially identical, such surrender shall not affect any action then pending nor abate any cause of action then existing, and the reissued patent, to the extent that its claims are substantially identical with the original patent, shall constitute a continuation thereof and have effect continuously from the date of the original patent.”
This means that for patent term extension purposes, the reissued patent is treated as a continuation of the original patent, particularly when the claims are substantially identical. The original patent’s grant date remains the basis for calculating the extension, ensuring continuity in the patent term.
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