What role does “reduction to practice” play in the written description requirement?
“Reduction to practice” is an important concept in patent law, but it’s not always necessary to satisfy the written description requirement. According to MPEP 2304.02(d):
“An applicant shows possession of the claimed invention by describing the claimed invention with all of its limitations using such descriptive means as words, structures, figures, diagrams, and formulas that fully set forth the claimed invention. Lockwood v. Am. Airlines, Inc., 107 F.3d 1565, 1572, 41 USPQ2d 1961, 1966 (Fed. Cir. 1997).”
This means that actual reduction to practice (building and testing the invention) is not required. A constructive reduction to practice, achieved through a detailed written description, can be sufficient to demonstrate possession of the invention. However, in some cases, especially for complex or unpredictable technologies, evidence of actual reduction to practice may strengthen the written description.
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